Forrester said:Before, I thought that the ranged-rogue hiding behind his allies might not be broken as the bad guys can just walk up and find him eventually -- the rogue may be hidden, but the baddies would know generally what square he was in. With Chameleon being at-will, they'll walk past the fighter and just not see him.
You can't hide behind your allies. You gain cover from ONLY ranged attacks at you. And you can't make a hide check on the enemies turn while he is attacking the rogue. Once the attack ends, you no longer have cover against only that ranged attack, and no cover means no stealth. On the rogues turn, nothing is attacking him, so he can't regain cover.
As for Chameleon, its a sweet ability, and its wording lets itself to be very powerful. The trigger in particular is interesting. "You are hidden and lose cover or concealment against an opponent." So this can be triggered if the attacker fires through your friend at you, giving you cover for just that attack, when the attack ends you have lost cover and trigger is off... BUT the first part says you are hidden. So to be hidden in the first place you must have some consitant non-situational cover/concealment. Because for your allies to give you cover, the creature must attack you, and a creature can't atack if they can't see you. If you can't be hidden in the first place, you can't use Chameleons trigger for gaining and losing the cover your friend gave you against only that ranged attack.