On the 2nd phase of damage, crota will NOT stay down for the duration of being hit, he will instead go invinsible WHILE DOWN and start spawning adds IN THE MIDDLE OF DAMAGE.
I wouldn't be mad if it was inconsistent enough to go under the radar of testing, but that crap has happened consistently, back-to-back. Causing a wipe due to being out of position when the adds start to spawn and being overrun because crota ended damage phase too early.