In a deck built to profit from discards, Dark Deal is quietly one of the strongest options
Similarly, cards like Crucible of Worlds, Ramunap Excavator, and Icetill Explorer in lands-matter strategies can turn fetch lands into repeatable value machines
Blade Historian Team-wide double strike ends games
These identity search tools will give you a great way to find cards for your deck later as well (simply remove that is:commander search to find all cards that are legal in those colours!), so give them a go and see how they work
Lord of the Undead, like Brimaz, is also a little on the expensive side
Theres no way, whatever your criteria, that youll get to the end and without asking, Steve, sure, but what about this card?!? I could have populated this list with staple commons like Counterspell and Elvish Mystic and probably been pretty accurate, from one way of looking at things