I mention Lutri, the Spellchaser here because it is banned as a companion , yet otherwise legal in commander
It does everything: It enables the strategy, its a payoff, and if you can turn it into Sephiroth, One-Winged Angel, which gives you an emblem for the rest of the game
Geiger, and gain victory by swarming over the battlefield with combo engine cards such as Hardened Scales, which offer infinite damage combos
Different printers use different safe margins, but the principle is consistent: dont park your most important details in the danger zone
Really cheap sweepers like Path of Mettle, Golden Demise, and Goblin Chainwhirler are still effective, but your opponent needs to have exactly the right answers