When using the Aid Another action, does it break invisibility? I'm inclined to say no, because you're not actually attacking a creature, you're making an attack roll against a flat AC of 10.
In melee combat, you can help a friend attack or defend by distracting
or interfering with an opponent. If you're in position to make a melee
attack on an opponent that is engaging a friend in melee combat, you
can attempt to aid your friend as a standard action. You make an
attack roll against AC 10. If you succeed, your friend gains either a
+2 bonus on his next attack roll against that opponent or a +2 bonus to AC against that opponent's next attack (your choice), as long as
that attack comes before the beginning of your next turn. Multiple
characters can aid the same friend, and similar bonuses stack.You can also use this standard action to help a friend in other ways,
such as when he is affected by a spell, or to assist another
character's skill check.
Best Answer
Yes, it does end. The general rules for magic state:
Aiding Another, because it either makes an opponent more vulnerable to attack or less able to attack back, is an offensive combat action. Here are the rules again, appropriately emphasized:
It's clear that this is directed specifically against a particular foe, and that you must be able to attack that foe in melee, and that your actions are directed against that foe. That's a textbook non-damaging offensive combat action.