Fateful hour If you have 5 or less life, those creatures gain indestructible until end of turn
Just by having Liliana, Dreadhorde General on the board, a player gets the ability to draw a card whenever a creature they control dies
In Commander, resolving one of these bad boys (or having one put into play via more nefarious means, such as with Muxus) is often enough for you to pull well ahead of your opponents on board
Cantrips like Opt and Consider are essential: they give me cheap card selection and the ability to dig for answers, and when paired with value engines like Talrand, Sky Summoner and Murmuring Mystic, they can add up to a massive board before long
This page should probably be updated more often than the other EDH Reference lists, due to time-sensitive nature of it, but I honestly don't think I'll update this very often