By combining casualty with lots of death triggers, like a Blood Artist or Zulaport Cutthroat, you can get even more value out of each Casualty spell you cast
It feels great to do
Unfortunately, the card does have a few downsides
If you're just trying to get a snapshot of a format but don't have time to read up on every card in a set, there are some categories of cards you should focus on
Ideally, you can start out early with cards like Siren Stormtamer and Fathom Fleet Captain, then cast your commander on the same turn you plan on fulfilling her end step trigger
They can still cast spells, so if they have a way to remove Overwhelming Splendor with a card like Krosan Grip they still can, but if it's tied to a creature, your opponents can be stuck under the Curse for the rest of the game