Here are just a few of the top tier Reserved List targets that could still ostensibly sustain another spike: Most of the demand for this card comes from its usefulness in Commander as an auto-include utility land for any creature based deck that can support its single green cost to regenerate a creature

Loser: Izzet Decks 2 Astrologian's Planisphere 1 Cori Mountain Monastery 1 Frostcliff Siege 2 Get Out 4 Into the Flood Maw 6 Island 2 Mountain 4 Multiversal Passage 1 Obliterating Bolt 3 Opt 4 Quantum Riddler 2 Ral, Crackling Wit 4 Riverpyre Verge 1 Roaring Furnace 4 Spirebluff Canal 4 Splash Portal 3 Stock Up 4 Stormchaser's Talent 1 Thundering Falls 3 Thundertrap Trainer 4 Torch the Tower 2 Annul 2 Detect Intrusion 2 Disdainful Stroke 2 Enduring Curiosity 2 Fire Magic 2 Obliterating Bolt 1 Pyroclasm 2 Spell Pierce No longer can Izzet decks exile Vivi Ornitier with Agatha's Soul Cauldron for an explosive burst of mana, nor can they leverage a suite of draw-and-discard creatures through Proft's Eidetic Memory
1 Sram, Senior Edificer 1 Sram, Senior Edificer While the above trio of cards are good, Sram, Senior Edificer is just better
Even with a just a simple Llanowar Elves in play, I draw three cards when Zegana arrives to the party
Will Rekindling Phoenix supplant Hazoret the Fervant, Chandra, Torch of Defiance, or Glorybringer any time soon