Was getting one-shotted in wave 7 of X-def.
Made it to wave 17 of the same run.
Was using Mr. Fantastic with Shulkie Team-Up active.
Pretty Sure it was Sinister doing the one-shotting, but not sure.
Granted I do not have him geared terribly great, but it still seems a tad over powered compared to the 10 waves that followed which included multiple bosses and grouped boss fights.
Only mentioning this in hopes it is fixed by the time I feel like going for Magik's last achievements :D
If anyone knows who to tag, or if this matter is already addressed please disregard.