The overkill bonus was just added very recently to Festival Battles. The bonus damage from Overkill can range from +5 all the way up to more than 1500 damage. This combined with a rogue's passive bonus can deal incredible damage.
A rougue's Evade ability does work against Overkill. Overkill works on Conquest lands too. One of our lands protected to over 500 damage per hit went easily.
Factors Affecting Bonus
Because of how new this feature is, the details are very uncertain. Overkill is not received when you're stunned. You will only get overkill bonus when the target is Polymorphed if you would have won without the polymorph.
- Your relative strength against your opponents (Must be work in progress - as proved not the case at present)
- Maximum health of the target