Tormod is definitely the stronger of the two because black works better with the archetype and zombies have considerably more support that spirits, but you'll realistically play either one in your gravebreak deck, assuming your colors support them
Eirdu, Carrier of Dawn / Isilu, Carrier of Twilight Eirdu, Carrier of Dawn grants convoke to cards in your hand that were not designed to have cost reduction, and Isilu, Carrier of Twilight gives you boardwide persist
Disturb is a mechanic introduced in Innistrad: Midnight Hunt, and has cards being cast from the graveyard in new forms
Things work slightly differently when we're rebalancing cards that have printed versions as well
They also had a sacrifice ability that required mana of that color to activate
Vincent's Limit Break will overwrite any previous effects that set the creature's power and toughness to specific numbers