Transform

Transform is an ability which irreversibly transforms a minion into something else. This removes all card text, abilities and enchantments, and does not trigger any Deathrattles.

Transformation is not an enchantment but rather a permanent change, which cannot be undone. Silencing the transformed minion or returning it to its owner's hand will not revert the transformation.

Transform is the battlefield equivalent of replace.

For cards which transform in hand, see: Transform in hand.

Trivia

 * Prior to Patch 8.0.0.18336, all druid Choose One transform cards had inconsistent wording, with Druid of the Claw not including the word transform, Druid of the Flame showing the end result as opposed to the stat change, and Druid of the Saber including both the word transform and related stat changes. This was eventually changed with the release of Journey to Un'goro to follow Druid of the Flame's formatting, with the new Shellshifter also written like this.
 * Prior to some time in early 2013, the word "Transform" was printed in bold text on cards such as Polymorph, and always with a capital letter. This suggests that it was previously a keyword (like Charge or Battlecry), complete with its own tooltip explaining the effect. The relative complexity of the mechanic (a non-reversible minion change) might justify this, with the ability the subject of some confusion during the game's beta.

Patch changes

 * Cards that "transform a minion into a random one that costs (1) more/less", like Evolve or Devolve, will now always re-roll the minion, even if no minion exists in the target-cost minion pool. The minion will be re-rolled at the nearest possible cost.
 * "Transform" in card text is no longer printed in bold, and is not capitalised.