I've been thinking about Equalise buffs a bit recently, nothing concrete but I had the same idea. Issue is that it makes the card too similar to Heal and Living Weapon. Especially since LW heals based on creature's max hp, Equalise would essentially heal based on attack instead.
Further, imo buffs to Equalise should keep Voodoolise as a viable combo. And these changes would... presumably damage the owner. An interesting idea to think about, though, especially as it makes BB/Equalise a thing as a suuuuper budget Unstable Gas, or having Pacify/Equalise exist for similar reasons, while also killing the creature. Imagining an Auburn BB spam Equalise otk is way too strong though. So it could just be hard coded, or use Catapult calculations
I'd be intrigued about max hp alteration, it has the same issues as above, and isn't really thematically sound, but differs it enough from Heal and LW to consider