Bear Trap is a 30 minute event. Typically done every other day, the more participation the better the rewards. Here is guide to dealing the best damage:

-Strongest rally leads should be close to trap.

-Join stronger rallies, before starting your own rally.

-Start your own rally if you are stronger then other rallies or if you have troops in your town and no one to join.

-When creating a rally, use your strongest heros.

-When joining someone else's rally, join with one of these heros if possible: Maeve, Red Cloud, or Emily.

-Set up Marches in the preset formations menu to make it easier to join quicker.

 

If you want some help setting up marches in the preset formations menu, let me know I can help!