1st:
Krirtu, 900k, 2 orbs, trigger: 3k AoE + hurt self 180k, OD 4k AoE + hurt self 180k
Oannes, 900k, 1 orb, trigger: 3x 3k + hurt self 180k, OD 1x 7k + hurt self 180k
Apsasu, 700k, 3 orbs, trigger: 90k AoE heal, OD 180k AoE heal
Ignore bottom, it does nothing ever. The other two really hurt, but will murder themselves quite quickly, making this a short fight. Weaker players might need to burn skills to kill the top two mobs safely.
There are no debuffs here, so if you're bringing a Friend's Kirin, you should use it on turn1.
2nd:
Umu Dabrutu, 6.5m, 5 orbs
OD: ~7k AoE
Trigger: First action: 20% DoT, 5t
Trigger: On Stun: ~5k AoE + Charm ?t + kill self (if you use Rage cuts, might not die)
The HARD type. You MUST have a countermeasure for that DoT or you WILL die. Thunder has some ways to deal with it:
1. Kill it on turn 1 (this is very difficult due to short wave1!).
2. Maiden's Prayer, Soul EX-skill for Cleanse. Or Andromeda's EX-skill Pure Garden (Debuff Prevention).
3. Cleanse from SSR Dian/SR Cyclops/R Indra (Gem Gacha!).
4. Friend's Kirin can give you Debuff Prevention - notice that there are no debuffs in wave1!
And once you've cleared that hurdle, remember that getting hit by that Overdrive will hurt. Good luck!