I'm barely clearing Ultimate with 23.4k attack power (I'm running a mixed team of Fire and Water, with Water as my main element). I actually found that Garuda's Overdrive during Rage was no more punishing than Expert. It hit me for about 3k. Definitely not 7k. The non-rage Overdrive hit for about 1k AoE with most of my attack debuffs on. She was definitely dealing out damage faster than I could heal, particularly once Nike went down.