Removal

Removal is the term used to refer to the elimination of minions from the battlefield.
 * Hard removal describes cards and effects that can neutralize minions regardless of most defenses, such as high Health or Divine Shield: usually Destroy or Transform effects. Every class has some form of hard removal option, although some such as priest are known for their range of removal effects.
 * Soft removal usually identifies cards and effects that can cause the death of an important target through damage: typically spells but sometimes including damaging weapons, abilities such as Battlecries, or minions with Charge.

The term is also used to refer to the quantity of cards which a player possesses with which to remove enemy minions: "He should have put more removal in his deck". Removal cards often work as flexible "answers" to problematic minions of the opponent, although other cards may fill this role as well.

Overview
Removal is reactive in nature, used to eliminate important minions played by an opponent. Nonetheless, it can be used offensively, such as by removing a Taunt minion in order to continue an assault on the enemy hero. Unlike maintaining board control using friendly minions, removal is usually effective straight from the hand, allowing quick destruction of threats or critical defenses without giving the opponent the chance to protect them.

The exact definition of removal seems to vary between players. For some, only spells count as removal, while for others weapons and minion cards with effects that function as removal also count. For example Doomsayer is commonly included in decks to serve as removal, but the card itself is not always considered to be removal, since it is a minion. Removal spells tend to offer an instant, one-card solution to threats that might otherwise at best require the sacrifice of several other minions or the use of multiple other cards, and at worst spell defeat for the player. Minions with removal effects, such as Anomalus, Sylvanas Windrunner and Deathwing, may provide removal through Battlecries, making their effects comparable to spells, or through effects like Deathrattles, providing a delayed and less reliable form of removal.

The purpose of a card can vary in different decks as well. For example, Frostbolt may be considered removal for Reno Mage, but a combo-piece for Freeze Mage.

Lack of hard removal can cause problems for players when encountering high-Health minions. On the other hand, hard removal sources are generally ineffective at mounting an offense to actually kill the opponent, so balancing removal and other card types is vital to building a strong and versatile deck.

Types of removal effects
Different types of removal effects have their pros and cons:
 * Destroy effects are the simplest and most common hard removal, ignoring Divine Shield and high Health, but still activating Deathrattles. Many destroy spells such as Shadow Word: Pain, Execute, and Naturalize have special conditions or drawbacks to balance their overall power.
 * Transform effects are excellent removal for Deathrattle (and Divine Shield) minions, since transformed minions don't actually die, but still lose their abilities. However, they leave the opponent with another minion that still needs a response, albeit probably a lot smaller.
 * Mind control effects may be the best hard removal of all, since they bypass Deathrattles, completely remove the minion from the opponent's board, and effectively create an equivalent minion for the player. However, these effects are usually expensive and hard to come by.
 * Entomb and Recycle's shuffle into deck effects also avoid most defenses, although Recycled minions may eventually return later in the game; on the other hand Entomb acts more like a delayed mind control effect.
 * Soft removal damage can often be targeted directly at the opponent if not needed for minion targets, making it more versatile than hard removal. On the other hand, the damage produced by such cards may not actually be enough to eliminate a desired target with a single card. Additionally, Deathrattles and even damage-related triggered effects will still go off. Removal such as Flamestrike and Explosive Trap compensate for fairly low damage by dealing it to multiple targets, but lack control.
 * Charge and Rush minions and weapons may be considered even less reliable than other soft removal options, due to their vulnerability to being blocked by Taunt, but can provide good card advantage, through trading for multiple enemies before being destroyed.
 * The Amazing Reno features a currently unique effect: making minions disappear, which removes them without triggering Deathrattles, adding them to the resurrect pool, or creating new minions. However, it affects both sides of the board.

Silence can be an effective alternative to removal for minions which rely on their abilities for value, with cards such as Lightspawn becoming almost worthless once their special abilities have been neutralized. It can also neutralize minions benefiting from enchantments, such as a Silver Hand Recruit with a Blessing of Kings. However, unlike true removal the base minion will remain, making this effective only in specific cases.

Types of removal
In addition to the mechanics of the card itself, removal can also be classified in many other ways.

Area of effect
Removal tools which target the entire board are considered to be Area of Effect removal tools. Cards such as Twisting Nether and Dragonfire Potion are examples of AoE, or area of effect removal tools. On the contrary, removal tools which only target one minion, such as Vilespine Slayer and Execute are considered single-target removals.

Time when played
The times in which the removal card can be first played plays a major role in deciding its purpose. For example, Execute can be played very early in the game, while Mind Control can only be played in the game, thus, Execute is an early game removal tool, and Mind Control is a late game removal tool. Additionally, the earlier a card is played in a game, the less damage it would need to do for it to contitute as a removal tool. Lesser Jasper Spellstone is widely considered early game removal despite only dealing 2 damage. Factors other than mana cost can impact this too, for example, Omega Devastator is a late game removal tool despite costing 4 mana.

Whirlwind effects
The term "whirlwind effect" is used to describe cards with abilities similar to that of Whirlwind's, dealing 1 damage to all minions. This type of card is generally not considered removal. However, at times when decks such as Token Druid or Odd Paladin, which use a variety of 1-health minions as their core game plan, are popular, they are commonly accepted as viable removal options. Examples include Dragonmaw Scorcher, Dreadscale, and Blood Razor.

Tech cards
Most tech cards are removal tools, such as Golakka Crawler and Hungry Crab. However, not all tech cards are removal tools, and not all removal tools are tech cards. These terms should not be confused. Removal tools which do not remove minions also fall under tech cards. Cards such as Acidic Swamp Ooze, Harrison Jones, and Weapons Project are examples of weapon removal tools, and Kezan Mystic, Eater of Secrets, and Flare are examples of secret removal tools.

Examples
Since a variety of card types can serve as removal, it is not practical to provide a complete list, but a few examples from different categories of removal are provided below. For more comprehensive lists, see the links above.