Destiny HERO - Dominance's second effect, wherein it allows the summoning of three level 9 or less Destiny HERO Monsters from the GY, upon destruction by battle or card effect, doesn't seem to trigger if the monster was destroyed by the effect of Fusion Destiny. Is that how it is supposed to be, in accordance with the card's Ruling? Or is it a bug?
P.S. Seems that it doesn't also trigger upon destruction by battle, either.
I see your problem. You sent Plasma to the grave. Dominance's effect requires you to summon 3 lv 8 or lower destiny hero monsters. If you don't enough targets, or targets that are eligible for special summoning, it resolves without effect. Because you only have 2 targets eligible for special summoning (Plasma is not eligible because it can only be special summoned from the hand) Dominance resolves without effect
try it again but don't use Plasma or Dogma