DelveDelve is a static ability that functions while the spell with delve is on the stack. “Delve” means “For each generic mana in this spell’s total cost, you may exile a card from your graveyard rather than pay that mana.”
The delve ability isn’t an additional or alternative cost and applies only after the total cost of the spell with delve is determined.
Multiple instances of delve on the same spell are redundant. (CR 702.66) (Each card you
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) from your graveyard while casting this spell pays for
.)
For each player, choose up to one target creature card in that player's graveyard. Put those cards onto the battlefield under your control. They're Zombies in addition to their other types.