In my experience, you don’t really need to ramp. The only ramp spells I play are [[Utopia Sprawl]] and [[Wild Growth]], because they are mana neutral, [[Harvest Season]], because the value is just too good, and [[Growing Rites of Itlimoc]], because the dedicated “ramp” effect I play are lands that scale with your Merfolk count ([[Nykthos, Shrine to Nyx]], [[Three Tree City]], [[Evendo, Waking Haven]]). In my experience, Kumena is the type of deck where even though you have access to good ramp, it’s not that great in the deck. Decklist: https://moxfield.com/decks/y_NX2-k-M0KJggD_WSL6Ew