You can obtain the Ursaring (2-Diamonds rarity) card by opening Pulsing Aura from Pulsing Aura set
Etali, Primal Storm It requires some protection and building around, but if you manage to attack with Etali, Primal Storm, you can easily outvalue your opponents quickly
Completing sets also forces you to buy the less popular cards at low prices, averaging out your cost basis
AddIronheart, Clever Champion to the mix, and those artifacts gain Improvise, too, letting you use them for paying mana costs
APPROACH 1: RAISE THE FLOOR The equation needs to change somehow in favor of these monstrosities, and the easiest way to do that is reduce the inherent risk of playing them
force your opponent into action, drop Vinnie, and suddenly opponents are trapped between giving you free lore, or using removal cards that cost them valuable tempo