Hurtily / Centipede / MFE isn't so bad
>Hurtily, and hits bots are only a threat for the first turn, but their attacks are shit so even if you lose the clash before you can buff you probably won't die. Then your debuffs should be able to pacify them, and it's just endless clash wins until the event strips them of surgery
>Centipede literally gives you a F R E E turn of set up
>Yet to challenge MFE, but he friendly fires his own units, so he shouldn't be too hard

Out of the packs I've done so far, the difficulty is like
Wuthering Heights Basement Rape Party (Fought on 12) > Green Zone (Fought on 13) > undying abno trio (Fought on 14) > Crabs (Fought on 11)
i would not want to do the basement on higher floors