1 damage isn't going to help so much against Paladins - the days of Muster for Battle are long behind us, and strangely Lost in the Jungle has not become a standard card for the class. It's only really effective at killing the very earliest Pirate Warrior plays (N'zoth's First Mate & Patches), too.
Basically, at best that spell is Arcane Explosion plus a little healing, and sometimes it even has a drawback of wounding/killing your minions. That doesn't seem so impressive.
In addition, Priest does have effective pseudo-AoE that's cheaper than 5: Potion of Madness and Shadow Madness. Save against very specific metas, I'd be inclined to think the Potion gets run over this as an anti-aggro tool. It's cheaper and probably often more effective.