(3/19/2021) After a spell with split second resolves (or otherwise leaves the stack), players may again cast spells and activate abilities before the next object on the stack resolves.
Keep him around long enough and eventually, it will be too late for your opponents to do anything to stop you
There are seventeen three-mana cards on my list so weve got to make some cuts here too

Academy Journeymage Acquisitions Expert Aegar, the Freezing Flame Allied Assault Angel of Unity Arcane Epiphany Archmage of Echoes Archpriest of Iona Ardent Electromancer Astrologian's Planisphere Azami, Lady of Scrolls Barrin, Master Wizard Base Camp Benthicore Black Mage's Rod Bloodline Necromancer Blue Mage's Cane Burakos, Party Leader Cascade Seer Champion of Wits Chilling Trap Circle of Power Coastal Wizard Commodore Guff Concerted Defense Cornered by Black Mages Coveted Prize Deadly Alliance Diviner's Wand Docent of Perfection Drana's Silencer Dreamstealer Emeria Captain Ertai, Wizard Adept Expedition Diviner Fever Charm Final Iteration Fissure Wizard Flame of Anor Frostpyre Arcanist Galecaster Colossus Gempalm Sorcerer Ghitu Journeymage Ghosthelm Courier Giant's Amulet Goblin Wizardry Great Hall of the Biblioplex Grotag Bug-Catcher Harmonic Prodigy Harper Recruiter Inalla, Archmage Ritualist Inalla, Archmage Ritualist Inspired Sprite Ixidor's Will Journey to Oblivion Jushi Apprentice Jushi Apprentice Kabira Outrider Kasmina, Enigmatic Mentor Kitsune Mystic Kitsune Mystic Kuja, Genome Sorcerer Lavamancer's Skill Lich Lord of Unx Lindblum, Industrial Regency Lindblum, Industrial Regency Mage's Attendant Malakir Blood-Priest Mana Sculpt Master of Winds Mentor's Guidance Multiclass Baldric

Provided you can cast an eight mana spell, this thing is easy to slot into many different builds
Check out the full MTG release schedule for this year to see what expansions are coming next, including Avatar: The Last Airbender