You must follow the normal timing permissions and restrictions of the spell you cast from among those cards
"Our core approach to Final Fantasy 7 was to capture the original PS1 game's narrative, while using Final Fantasy 7 Remake and Final Fantasy 7 Rebirth's modern aesthetics to push the fidelity of each character design, story moment, and memorable location to the next level," said principal narrative game designer Dillon Deveney
Derevi lets you tap or untap any permanent when a creature you control deals combat damage to a player, which is great for Najeela since she makes more creatures with every attack, and has that five mana extra combat ability
Thats essential to trigger all your payoff cards, but it also impacts certain spells like The Tarrasque
Even if you choose to build her on Terra on her own, mastering the graveyard can yield some incredibly potent effects, so long as you play your cards right
I also like the flowing watery aspects of the angelic being in Fiery Justice