carborundum
Adventurer
Having read many conflicting opinions and being fed up arguing with my players it's time to start another polymorph headache thread. Sorry guys, I'll have to rely on your patience here 
The situation is the 14th level party I'm DM-ing for. The game is going well (all the way from 1st), the characters reasonably balanced, the players reasonably well-behaved and not uber-tweaking every single week. When the going gets really tough though, the wizard ends up casting polymorph and becoming a war troll - usually after casting stone body. He can still cast (since polymorph from the PHB is based on alter self which makes specific exceptions for class abilities and equipment - or something).
It doesn't seem fair that he can overshadow the fighter at fighting while also casting and being invulnerable. Okay, "just" for 14 rounds but still - that's a major combat and most of the session that the rest of the players look a bit down.
Am I doing it right?

The situation is the 14th level party I'm DM-ing for. The game is going well (all the way from 1st), the characters reasonably balanced, the players reasonably well-behaved and not uber-tweaking every single week. When the going gets really tough though, the wizard ends up casting polymorph and becoming a war troll - usually after casting stone body. He can still cast (since polymorph from the PHB is based on alter self which makes specific exceptions for class abilities and equipment - or something).
It doesn't seem fair that he can overshadow the fighter at fighting while also casting and being invulnerable. Okay, "just" for 14 rounds but still - that's a major combat and most of the session that the rest of the players look a bit down.
Am I doing it right?