they have increasing degen, starts at -1, goes to infinite over time....it makes it so they cant stay alive forever (you can only keep them alive til about -20 degen....)
no it doesnt, well...it does, the max degen they can have is 10...but they can have 20, which would cancel out verattas sacrifice and leave them at -10
-10 health degen is as bad as it can get, so yes, a team with 2 or three necromancers using Verata's Sacrifice could technically keep an army of minions alive forever.