Gandalf comes with four abilities, you can choose each one until you've chosen them all, each time you cast an instant or sorcery spell
Otherwise, Vial Smasher the Fierce is oddly appealing, which is strange for me to say because I'm not usually a fan of aggressive commanders
Teysa Karlov I place Teysa Karlov in the #1 spot today thanks to its extremely powerful ability to double your triggered abilities
Dungeons of Death Dungeons of Death is helmed by Sefris of the Hidden Ways
With these cards, we can simply cast a Glorious End to make our opponent skip their turn and then, when it comes time to pay the price during our end step, counter or exile the "you lose the game trigger." Problem solved
Legends are historic, after all