(It's an artifact with ", , Discard a card, Sacrifice this token: Draw a card.") Whenever you discard a card, put a +1/+1 counter on Ivora
Archaic's Agony Avacyn's Judgment Banefire Blaze Bonfire of the Damned Burn from Within Calamitous Cave-In Cataclysmic Prospecting Chain Reaction Choco-Comet Comet Storm Conflagrate Crackle with Power Crater's Claws Delete Demonfire Detonate Devastating Dreams Devil's Play Disaster Radius Disintegrate Draconic Intervention Dwarven Catapult Earthquake Electrodominance End-Blaze Epiphany Eternal Flame Fall of the Titans Fanning the Flames Fault Line Fear, Fire, Foes
A player loses the game after having been dealt 21 combat damage from any one of them, not from both of them combined
Toxin Sliver Market Price: $3.52 A four-mana 3/3 is far from playable in Constructed formats, but that's the beauty of Slivers
Urza can also pivot to a more Stax and Control game plan, because having options is always nice