Appearence[]
XA-60' appears identical to A-60'[1] the only difference is XA-60' is purple.
Mechanic[]
Multimonster Secundus Is an entity that comes after A-60' (Multimonster Prime). It will flicker the flashlights and make your screen purple while rushing backwards (it waits 2 seconds before rushing). Once it despawns, there is a chance for more of it to appear. After it's gone, your screen won't be purple anymore, however, there is a chance of A-60' or Multimonster Prime Secundus spawning after that.
How to Survive[]
In case XA-60' spawns, remember what you learned from A-60'.