Of course, they could exert for other reasons and avoid having to challenge, but if you can get something big enough of your own exerted, your opponents characters will crash against it and take themselves out
Will of the Temur This six-mana sorcery will do one of two things, or both if you control your Commander
I also like Dovin here on his ultimate, but he's more about the -1 than anything else, so get a little frisky with the card drawing
Finally, you have the activated ability to instantly untap a creature or land to best suit the interactions on the stack
However, odds are your thirst for Astarion could remain unquenched
Its a 2/2 blue Merfolk Wizard for three-mana that lets you take control of a creature with power less than its own for as long as you control it