The Game Awards After Party allowed Arena players to try out Elspeth, Suns Nemesis
Kaalia lets her controller cheat on mana and get those creatures into play as early as Turn 4 (without ramp and with a Haste provider, like Lightning Greaves) and even sooner with mana acceleration, like Sol Ring
To be clear, you need to pay the two Energy if you have it
Here are a few options that each one can search: Trinket Mage - Esper Sentinel, Sensei's Divining Top, Shadowspear Tribute Mage - The Soul Stone, Arcane Signet, Grinding Station Trophy Mage - Buster Sword, Extraplanar Lens, Simularcum Synthesizer Transit Mage - The One Ring, Roaming Throne, Iron Man, Titan of Innovation Tribute Mage - The Great Henge, Knowledge Pool, The Immortal Sun #3 - Harmonic Prodigy Harmonic Prodigy