I suggest swapping spellswallower with backlash or another upgrade. As long as sheoul beast retains backlash on base no one will want to run it on pain of nuking they're shrine every time they sacrifice a champ. A rune is so much more attractive when it has versatility rather than branding it with an ability that makes it incompatible in a faction that depends on a spell like sacrifice
Funny thing happenned to day. I killed my shrine with a sacrifice. Silly backlash. I am not used to playing UD sacrifice. I need to get out more and visit the other factions. I love UD blood theme. It is so much fun. Hard to set everything up the way I want, but when I get power turns they are fantastic. Rain of blood great spell.