Template:Sylvanas Windrunner strategy
Sylvanas Windrunner is a card that can easily change a game, quickly. With her Deathrattle it is very easy to make yourself very powerful and crush your opponent with their few remaining forces after Sylvanas Windrunner is dead. Furthermore, it may force your opponent to play around Sylvanas, in fear that one of their powerful minions may be taken from them. But beware, she can be useless if you are in a bad situation, as she will be targeted as soon as possible and you will probably get nothing of value for 6 mana. Without a minion to steal, she is a mere 5/5 for 6 mana.
Destroying a Sylvanas of your own is sometimes a strategy to consider. For example, if your opponent only has one powerful minion on the board and you play Sylvanas followed by 
Power Overwhelming on her, this is effectively a seven-mana, two-card Mind Control. This is of course usually most desirable when the opponent possesses a single highly powerful minion which the player is otherwise unable to counter. Shamans are also able to utilize her deathrattle effectively with use of cards like Ancestral Spirit and 
Reincarnate. Another strategy involves destroying her with Shadowflame to clear any weaker minions and take control of one larger than 5 Health (or with Divine Shield), although this minion will still suffer the damage from the Shadowflame. Another strategy is using Brawl while with a Sylvanas on the field, this way ensuring the surviving minion will be on your side.
A less extreme (and more card efficient) alternative is to run Sylvanas into a target with the express intention of destroying her. This play usually sacrifices Sylvanas' long-term trading efficiency in exchange for immediate control of a valuable minion. It may provide the additional benefit of dealing damage to an enemy minion, but in many cases that is also the minion that will be stolen, making this more of a drawback. The ideal implementation of this strategy is to use Sylvanas to trade with a valuable enemy minion, before allowing her Deathrattle to gain control of another, hopefully even more valuable minion. In some cases, such as if playing against a lone Ragnaros the Firelord, it is necessary to directly trade Sylvanas for control of the enemy minion, even if that means damaging it in the process. In this case, Sylvanas can be traded for an 8/3 damaged Ragnaros.
Sylvanas is a strong addition to decks that can create 1/1 copies of her such as 
Shadowcaster, Herald Volazj, and 
Barnes, as these 1/1 copies can be destroyed easily via trading, and for some classes the user can destroy Sylvanas themselves to control an enemy minion unharmed.
Counteracting Sylvanas's Deathrattle can be tricky, especially if your opponent plays her against you to catch you out with only one or a few good minions that her Deathrattle can hijack. Mages and Shamans can handle Sylvanas efficiently with Polymorph or Hex respectively, while Silencing Sylvanas with Ironbeak Owl or Spellbreaker makes the situation more manageable, but still leaves a substantial 5/5 on the board; in either case such cards may not always be at your disposal. In the event that Sylvanas is played and you have no ways of countering her Deathrattle, a risky but possible solution is to introduce several low-cost or low-value minions to the battlefield; since her Deathrattle targets a random minion, having more minions on your side of the board will lessen the chance that one of your stronger minions will be taken from you when Sylvanas dies.
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