For regular upgrades I highly recommend: Vito, Thorn of the Dusk Rose, Mondrak, Glory Dominus, Anointed Procession, Parallel Lives, Eerie Ultimatum, and you can also run the Cat Oven combo with Cauldron Familiar + Witch's Oven + Clock of Omens, and there's the Ballista Combo Heliod, Sun-Crowned + Walking Ballista, and finally the Exquisite Blood Combo since the deck already runs the other piece Sanguine Bond One Down, Three to Go
A free creature token whenever you make tokens, on a decent body that can grow makes Quina decently
Having a strong Adventure bumps up the card, but its still good at five mana
Since Simic typically loves ramp, this seems really strong there
Given that the Illumineers Quest set can be used as a standalone, board game-style experience or by utilising your existing Lorcana card collection is also a very smart choice