Ill just type first thoughts that come to mind:
If youre playing a reanimation deck,
opt for effects you want on creatures. I wouldnt save up for a
damnation, id rather run
massacre girl. When in the graveyard it makes your commander a boardwipe with him sticking around. The same goes for draw,
Arcanis the Omnipotent makes your commander into a repeatable draw 3 + the added benefit of being able to bounce it, if you need to dodge removal or just want a different effect. So just look at your instants and sorceries, type what you want to happen in scryfall and only look at creatures.
To answer your question regarding mana rocks: I think 10 ramp spells are totally fine and running manarocks in a deck which has green and therefore landramp to its disposal is something Id most likely wouldnt want to do.