Since Modern clocks in at over 50 playable decks, Im only going to cover the main ones, and hopefully from those you can get a baseline to figure out the rest yourselves
If any part of that creature's head is higher than the bottom of the bar (that is, if it would hit the bar), the creature is a legal target
If you want to take this deck to the next level, Nexus of Fate goes infinite with Zethi so long as you can attack without losing your commander
Saw in Half Saw in Half is another amusing design that first debuted in Unfinity
however, it does provide a few things we might be interested in in the right deck
As for black mana, Eyeblight Massacre is one of a few one-sided sweepers in Commander Legends , giving -2/-2 to all creatures except Elves