Azra equiped Explosive Start and Chain Lightning. (Chain Lightning is not necessary)
Recall healers and place them again, this will cause an explosion which does 5468 damage to a 5x5 area.
1. Healer is the cheapest unit.
2. Inspire will last a long time if you recall healers after they attack.
I just successfully get to wave 111 without a very good skills setting. (I stopped to make explosion after wave 100.)
** If you pause the game to recall and place healers, it may take 3 hours to get to wave 100.