I am basically done with my AQ6 guide, and then I should do a AQ7 guide.

But, in short, AQ7 wave1 usually has ONE mob which is dangerous. In the case of Thunder, it's the top one.

Wave2 generally has two types. Three of them are FUCK YOU YOU DIE LOL and three of them are a joke (to veterans). Thunder is one of the former, deploying a 20% HP per turn DoT (no upper cap) on turn1. For five turns. Yes, that WILL kill you if you don't deal with it. It's even worse in Thunder AQ since Wind has very, VERY little access to debuff prevention and Cleanse through Hime. Anyway, the Overdrive is also a "game over" style hit, as it will blast you with a 10k AoE. Against this type of enemy, gather burst from wave1 and full burst it.

Wave3 is an interesting one. As always, it's the same with all elements. The important thing is, if you use all four colors of abilities, the boss will waste a turn BPing herself! This is AMAZING design as it allows weaker players to actually plan their teams and make this boss much, MUCH easier for you. This can be done twice, so her blops go from 2 to 4. Additionally, she gets angry if you use NO abilities on a turn, so if you're weak, try to also bring somebody with a very low CD skill or two.

Until I get my AQ7 thread done (or until somebody else does it, but who am I kidding, only Kitty around here does stuff these days), you might want to look up shit from the DMM wiki.