The up and downsides here are much like with consistency, where the harder you commit to your theme the more likely it is to work, but also the more likely you are to run into problems you can't solve with the tools available to you
Drown in the Loch is an extremely powerful card from Throne of Eldraine
That means we can do ki counters in Esper and use a reanimator shell with my favorite card from this block, Gifts Ungiven
Iroas, God of Victory: A great option for going wide and controlling the board with damage-based wrath effects
These are generally soldier-specific, so although you likely want to run an Akroma's Will, I don't list generically awesome cards like that here
Mirrodin Fun Deckbuilding 1: Colorless I will start this multi-post deckbuilding experiment by looking at the colorless artifacts in my Mirrodin selection pulled from a tournament pack and five booster packs