Quick guides is a series of articles that are mostly aimed at new/intermediate players. Goal of those guides is to explain common terms, strategies etc. in a concise and understandable manner. If you're looking for more in-depth guides, deck lists etc. - check out other articles on the site!
This one is going to be about deck types. I'll talk about the basic archetypes, how do they look like and how to tell them apart. Then to make things just slightly more complicated I'll also add secondary types into the mix.
Disclaimer: Those types and division into "primary" and "secondary" isn't official, you can most likely categorize decks in different ways, but I'm trying to show the most common one. Yes, it's subjective and probably not perfect, so if you found a better way to categorize decks, please share it with me!
Primary Deck Types
There are three primary deck types and they're all very different. The main difference is the "speed" at which they play the game (tempo), which also determines their role in each matchup. Other differences are the average card's mana cost, balance between the proactive and reactive cards, the usual win condition etc. Let's start with those that are easiest to describe:
Aggro decks, just like the name suggests, are aggressive. They play a lot of small minions with the intend to have very strong early game, thus punishing opponent's life total and trying to kill them as fast as they can. Their mana curve is really low, because they want to have a good play each turn, starting turn 1 and having a lot of low mana cards nearly guarantee it. They like to play "snowball" early game minions that can get out of control really quickly if not answered (e.g. Tunnel Trogg, Mana Wyrm, Darkshire Councilman). Besides normal minions, Aggro decks usually play so called "burn" cards. Burn card is anything that can immediately deal damage to opponent without requiring any setup and even from the empty board. So burn cards are mostly damage spells like Fireball or Lava Burst, but minions with Charge (e.g. Argent Horserider, Kor'kron Elite) or weapons (e.g. Eaglehorn Bow, Doomhammer) can also be classified as burn (but those, unlike spells, can be stopped much more easily with the help of Taunts). Aggro decks want to play proactively in every matchup - the only reactive cards/removals they have are burn and they prefer to keep those to deal face damage. This type of deck has little to no comeback mechanics - once it falls behind, the only way to win the game is to get enough burn.
Aggro decks run out of cards very fast. Some of them utilize cheap ways to refill the hand, but they're still scarce. Combining it with the low cost of the cards, they rarely stand any chance at winning the "value" game. Aggro game plan is to play as many early minions as possible, try to sneak in as much damage with them and then close out the game with burn cards. The goal is to finish game by turn 5-8 (depending on the exact deck), this deck type struggles at playing long games (because against other Aggro one kills another before the late game and in slower matchups opponent eventually outvalues you if you don't kill him in time).
Control decks are polar opposite of Aggro. Once again, going by what the name suggests, Control decks want to control the board and win this way. Of course, there are a lot of games that you can't win by simply controlling the board and not doing anything else, thus Control decks will often play big minions or other ways to finish the game in the late game, once they stabilize. They don't run a lot of early game minions - a lot of Control decks don't even play any 1 mana minions (as opposed to 8-10 1-drop Aggro decks might run). They focus on removing opponent's stuff rather than playing their own. And thus, they also have a lot of AoE removals as a way to deal with the board flood. Most of the Control decks have some way to (almost) completely clear the board - a comeback mechanic (e.g. Equality + Consecration, Brawl, Twisting Nether). Those are also the ways to get card advantage - they are efficiently dealing with multiple minions opponent has.
Control decks run a lot of cards that are low on tempo, but high on value. It's common to see cards like Acolyte of Pain (much weaker stats than an average 3-drop, but gets card advantage) or Elise Starseeker (weak 4-drop, but has a potential to get a lot of value in the slow matchups). Of course, they also need to run some faster cards as a way to adapt to the meta, but they still play most of the games reactively. They also are low on the burn cards, unless that's specifically their win condition. Instead of Charge minions, they often prefer to run minions with Taunt to stop the aggression. Control decks also need to play other survival tools, like Healing/Armor gain or ways to stall the game (e.g. Freeze effects in Mage) to not get rushed down by faster decks.
Control deck's game plan is to, well, control the board, draw the win conditions (usually big minions or some sort of combo), drop them and win the game this way. Against faster decks they mostly try to survive - surviving as Control and running opponent out of cards most likely means that you win in a next few turns (by outhealing the damage they deal, by killing them with big minions etc.). In slower matchups they play the value game, try to get as much as they can from every card they use - those games often end up in Fatigue when both players draw their whole decks, so using every resource wisely is the priority. Goal of the control deck is to stretch the game for as long as they can, as they have a clear advantage in the long matches.
Midrange decks in Hearthstone are something between Aggro and Control. They are hardest one to classify, because sometimes faster Midrange lists look almost like Aggro and slower ones almost like Control. Midrange deck is the one that adapts to the situation and can play either role depending on the situation. Vs Aggro decks, they might assume the Control role and try to remove everything enemy plays and outvalue them. They run bigger minions and (usually) some AoE removals, so they can also stretch the game a bit. They don't run as much healing and defensive tools as Control decks do, but instead they can close the games quicker with strong minions. Then, against the Control decks they try to be the aggressors, putting pressure on the enemy with mid sized minions. On the one hand, they aren't as fast as Aggro decks and won't likely kill enemy around turn 5-6, but on the other they can afford to play a longer game and their minions are much harder to remove (they are out of range of a lot of AoE clears and small removals). Best Midrange decks were known for a huge versatility and the ability to adapt their play style against the deck they're currently facing.
Even though most of the Midrange decks run some small minions, they aren't as important as in the Aggro. Midrange can usually afford to skip turn 1, maybe even turn 2 and still win the game. What is more important is the mid game curve. They absolutely want to hit the 3-drop into 4-drop into 5-drop etc. and have a strong play every turn. Midrange decks usually win the games with minion pressure - they constantly try to have 5+ attack on the board to threaten opponent's life total and force them into using all their removals, just to fill the board again with more minions. They also run some removal - AoE to counter Aggro decks (e.g. Swipe, ) and high tempo single target removal to get the upper hand in Control matchups ([card]Mulch, Hex)
Midrange decks might be seen as the most "consistent" out of 3 (as in hardest to counter, having least bad matchups), because they combine the good sides of both types of the decks. You might say that Midrange deck is a jack of all trades, but with the right build and right hand they can be very successful in pretty much every matchup. That makes Midrange the most common deck type on the ladder through the history of Hearthstone.
Secondary Deck Types
Pretty much every deck belong into the one of the above categories. While some are hard to classify (e.g. Zoo Warlock, depending on the build, can be seen as an Aggro or Midrange deck) or may be something in between, it still has the main type. Secondary types (subtypes), however, are more tricky. Some decks can have a few secondary types and some of them don't even have any. Arguably there are even more subtypes than the ones I'll list below, but I've tried to include the most common ones through the history of Hearthstone (some of them aren't popular right now, but were in the past).
If you don't know what "Tempo" means in Hearthstone, check out my previous article from this series. This one is pretty weird, because decks described as "Tempo" in Hearthstone aren't necessarily the highest tempo decks. Aggro decks are usually higher tempo ones than decks called "Tempo". Decks like Tempo Mage or Tempo Warrior are pretty much Midrange decks, so they can be played pretty slowly if it's necessary. Tempo decks in Hearthstone are more about the fact that they have cards that clearly boost their tempo, they want to stay ahead and be in control of the board AND they can make clear, big tempo swings.
And so, for example, Tempo Mage can swing the tempo heavily with Flamewaker combos. Turn 4 Flamewaker + Coin + 2x Arcane Missiles is a huge tempo swing in a lot of scenarios, as you put a 2/4 minion on the board and deal 12 damage in total. Tempo Warrior can swing the tempo with multiple Whirlwind effects, weapons and Execute - clearing whole opponent's board and playing 1-2 minions yourself is not uncommon as a Tempo Warrior.
Both decks also want to play their own minions while removing opponent's stuff at the same time - keeping the tempo in their favor.
So you should generally associate "Tempo" decks with Midrange decks that want to stay ahead, remove your stuff all the time and swing the tempo if they fall behind.
Combo is a deck's win condition. Combo decks run a few cards that are most likely pretty weak apart, but when put together they form a great win condition. Most of the combo decks run "damage" combos and they use them to finish the game by dealing a lot of damage to the enemy. E.g. Combo RenoLock runs the Leeroy Jenkins + Power Overwhelming + Faceless Manipulator combo for 20 damage in total. But some of them also run board-oriented combos, like Grim Patron shenanigans in Patron Warrior. Most of the combo decks are Midrange and Control, but they usually run more card draw then normally in order to draw the necessary combo cards more consistently.
Combo decks also often use Emperor Thaurissan as a way to activate their combos. If a certain combo costs more than 10 mana, they need to reduce the cost with Thaurissan. And so playing a 11+ mana combos is possible (although they shouldn't be more expensive then 12 mana, because that would mean you have to hit 3 or more exact cards).
Decks that don't run the combo as a main win condition, but rather have some sort of burst finisher (e.g. Control Warrior with Grommash Hellscream) or a bunch of cards that loosely synergize with each other aren't usually called combo decks.
Flood deck is a deck that has a game plan of, well, flooding the board. Those kind of decks place quantity above quality and just want to have as many minions on the board as possible for as little resources. Since playing a lot of small minions is an Aggro trait, most of the flood decks are Aggro, but some might also be Midrange. Flood decks try to overwhelm enemy with the amount of stuff they play. They play the cards that can quickly refill the board after it getting cleared - Forbidden Ritual is a great example. They also try to play sticky minions that won't just go away after getting AoE'd (e.g. Argent Squire, Possessed Villager). There are much less of those in Standard now, because cards like Haunted Creeper, Muster for Battle or Imp-losion were really crucial in Flood deck's strategy. That's why flood decks aren't as popular in the Standard anymore. The only popular flood decks right now are Zoo Warlock and Aggro Paladin. More totem-oriented Midrange Shamans can also be called flood.
I've put those two together - even though those terms are slightly different, they often describe the same decks. Generally, fatigue decks make fatigue their win condition. They want the game to get into the fatigue and then win by either having more health or more cards than the opponent. Fatigue decks don't necessarily plan to force enemy to draw the cards (that's not their main goal), that's what Mill decks do. Besides fatigue being their main win condition too, they also want enemy to draw cards to get there faster. They play cards like Coldlight Oracle or Naturalize to force enemy to draw the cards, possibly even overdraw. Even though those two types have the same win condition, they can be completely different. For example, Fatigue Warrior is an incredibly slow, control deck that want to stall the game until it's very late with a lot of removals, utilize the insane Armor gain from Justicar Trueheart to have much more health than opponent has and then win the fatigue war this way. On the other hand, Mill Rogue wanted to play much faster games. He forces opponents to draw a lot of cards with Coldlight Oracle and then uses Gang Up to put more copies of them into his deck. So in best case scenario, Mill Rogue has 8 Coldlights in total, while 6 of those are "extra" cards in the deck. It means that the game gets into fatigue even as soon as turn 7-8, but then opponent is ahead in fatigue by a lot and takes way more damage. We also had Mill/Fatigue Druid, which was something in between - Druid wanted opponents to draw more cards, but he also played a lot of removal and defensive stuff to stall the game (since he couldn't copy Oracles like Rogue did).
This subtype got hit really hard in Standard with Deathlord being gone, but it still might be played in the Wild.
Ramp decks want to cheat the mana curve. They want to be ahead in terms of mana. They use tools that permanently or temporary increase their available mana. Currently Ramp is the territory of Druid - even though there are SOME neutral or other class tools to slightly ramp up (e.g. Pint-Sized Summoner, Unstable Portal Naga Sea Witch or Emperor Thaurissan, they are bad or just too slow to call certain deck a "ramp deck". Maybe in the future we'll see more, but currently Ramp Druid is the only one from this subtype. The deck plays cards like Innervate, Wild Growth, Mire Keeper and Nourish to get ahead in terms of mana. Once it's ahead, it starts dropping big minions when enemy is still at 3-4 mana and often can't deal with them.
Some people have argued that Handlock should also be called a ramp deck, since playing a turn 4 Mountain Giant or Twilight Drake (let's say 4/9) is like getting those out ahead of the curve (you can't normally play such a big minions without any negative effects so early), but this one is up to discussion, because those 2 cards are the only ones like that in the whole deck.
That's all folks. Even though the article was targeted specifically at new players, who still don't know much about this game, I hope that even the more experienced have learned a thing or two. If you still have any questions, feel free to ask in the comment section below.
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Good luck on the ladder and until next time!