Ureni's Rebuff Sending a creature back to its owner's hand is usually a better way of dealing with it than sending it to the graveyard
Players looking to construct Arna can go all in on Equipment, Enchantments, or a mix of both, with plenty of ways to Voltron your way to lethal Commander damage in one fell swoop, or otherwise build up a wide board through unorthodox means like Bestow
There are 565 Zombies legal in Commander
Put the rest on the bottom of your library in a random order
Sword of Light and Shadow Sword of Light and Shadow is another Mirran sword with a more niche triggered ability
Note that sagas only sacrifice themselves as part of the resolution of their last chapter ability, or if they somehow end up with more counters on them than they have chapter abilities, which very rarely happens and doesnt prevent their chapter abilities from triggering anyway