Mortivore is a good example
If any of them require targets, those targets are chosen as you put the abilities on the stack, before any of those abilities resolve.
When Sam triggers, bring the Walker back to your hand and cast Phyrexian Walker
Rakdos colors also provide easy access to double strike, menace, and other helpful abilities that can help damage get through
Stifle targets abilities on the stack, but mana abilities never go on the stack, so there is no legal target
Roaring Earth In decks like Slogurk, the Overslime, Obuun, Mul Daya Ancestor, heck, even The Gitrog Monster, youll be playing enough lands with your commander out to turn them into a threat all on their own