I don't know how others will feel about this, but I ran into this problem the other night while running AoW. The Wizard of the group, who out-of-character had been rummaging through the MM to find a good polymorph form to use, decided to turn into an Annis Hag, due to their +10! Natural Armor bonus, 2 claw attacks, each with a free grapple, a rending attack if both claws hit, and the ability to continue to claw/claw/rend, while maintaining the grapple.
After making short out of what was rest of the encounter, I think I decided on the following...
As the DM, I'll hold on to the MM, and make hopeful-polymorphers/wild-shapers make appropriate Knowledge checks to see if they know about a particular creature's abilities, let alone if it even exists! The Wizard's player, however, felt that he would then have to spend too many of his skill points on the appropriate Knowledge skills.
Also, that would pull the game to a standstill, as every form he wants to ask about, I, personally, would have to stop, and decide what he'd know based upon his check.
Anyways, does anyone have any thoughts on how I might be able to balance the power of the spell, without crippling it, and/or slow down playtime? Or just any thoughts in general as to how this course of action sounds?
Thanks in advance everyone!