Choose a minion. Discover a new minion to transform it into.
How to get
Polymorph: ??? is unique to the Arena and can only be obtained via drafting it during an Arena game.
The way to use Polymorph:??? to its full extent to either polymorph a weak minion from you into a high cost minion or morph a high cost enemy to a low cost minion.
It is quite similar to Polymorph: Boar. You will probably use it on a weak minion (like a Wisp or a minion focused on its Battlecry), but you can also use it on a very strong enemy; though regular Polymorph is better at that, this can be used in dire circumstances.
Don't just look for the minion with the worst stats when Polymorphing your opponent; similarly, don't look for the minion with the best stats when Polymorphing your own. Look at its ongoing abilities and Deathrattles (remember that Battlecries are useless). For example, give your opponent a Rattling Rascal, and yourself a Kalecgos.
When Polymorphing your own, choose only abilities that you can utilise; for example, if you have a lot of cheap spells in hand (but not in danger of overdrawing), you can choose Archmage Antonidas over Zzeraku the Warped. Also keep in mind your enemy's cards when Polymorphing your opponent's minions. If your opponent has an Archmage Antonidas and 2 Sorcerer's Apprentice on the field, DON'T give him another Sorcerer's Apprentice!!!!!! Even if the others are Giants (unless, of course, you can remove them).
- Polymorph: ???'s artwork comes from the World of Warcraft Trading Card Game "Crown of the Heavens" series, for the card Hexamorph.
- Patch 10.4.0.23576 (2018-03-12): Added.