Polliwallop is our removal spell, and it's a good one, dealing damage equal to twice the power of a target creature we control to one of our opponent's creatures, typically for just one mana (thanks to its cost reduction) at instant speed
Gaining life in Commander usually needs to accomplish a goal, which is something that Celestine does well
If you have very expensive vintage Magic cards, I would definitely look into the larger auction houses as they have the unique advantage of getting you you national attention
9 Patchwork Banner Its All Coming Together Bloomburrow brought with it a ton of great kindred pieces, and perhaps one of the best of them is the Patchwork Banner
In fact, those two cards chain together superbly: casting a Rampant Growth on turn two allows you to cast Explosive Vegetation on turn three and start turn four with seven lands in play
This everything but Black powerhouse will get heavy play as a Commander, as four-color options usually just show up well at the kitchen table