I am wanting feedback about a game I did last night...to determine if i was being too hard on my players...
No you where not hard on the players based on the information provided. Hammering makes noise, so unless they thought they could make short work of the 3 trebuchets before the guards woke up... it was bound to fail without some additional support/lookouts. Now the part about being captured by TK, that might be boarder line (without known specifics). Though they did have options once captured from their spell inventory (even w/o getting into specific races). 28 Faeries (IINM) casting Faerie Dance, I feel sorry for those guards (it would be pretty improbable to roll Save vs Magic that many times in a row), which could have let them out.
As Shadowhawk suggested, I'd have them doing similar actions. Faeries are supposed to be pranksters, so they should know how to engage in stealth to setup their pranks/sabotage. Activities that create lots of noise to setup aren't stealthy.
I would add:
We can't forget about their magic arrows, which could be employed in a variety of ways:
-as an opening salvo when the attack happens, they can potentially take out ~25% of the force (in your game session) if they don't make their saving throws and depending on the type of arrow. If multiple volleys can happen...
-those arrows could have been used to disable various soldiers temporarily, and then more long lasting (physical bonds) so they could slowly have caused attrition and even opened up weakness in the defense of the captured village/keep
The Faeries could also detail a team to transfer weapons/keys/tools to prisoners so they can effect their own escape (maybe give them an idea on when to make their move) so that the Elven Wizard's forces have to split their attention.
They could also target any soldiers that are sleeping by tieing them down, disabling locks and hinges so they don't work even if they did manage to get free if they are in buildings.
They might have also been able to create a faerie ring around the trebuchet location(s). Though the actual creation process might or might not be possible (GM's call). It depends on how fast they can build one, and if the trebuchet location is viable.
They could target them with various Faerie foods, possibly even look for mass distribution of Mushroom Tonic or other drinks that can be dispensed while the targets sleep. Different drinks probably have different amounts to be effective, and they have varying effects. I'd look at the Mushroom Tonic (small dose) since you essentially shrink them down to Faerie size for at least an hour, so if distributed at the right time and to enough targets they would be essentially useless (being 6" tall in the middle of winter, without clothes that fit, and weapons likely being ineffective) in the defense of the captured village.
