Anything you want to accomplish with Rionya can be attempted with Delina, Wild Mage too, but its much harder to pull off, given she makes a tapped and attacking creature, and given that creature will be exiled at the end of combat which will happen as you move to the next combat phase
Table of Contents show What Are Board Wipes in Magic
Is Shadow the Hedgehog legal to play
Legendary Creature - Human Druid Color tag templates(None) Elvish Mystic Creature - Elf Druid Color tag templates(None) Fyndhorn Elves Creature - Elf Druid Color tag templates(None) Galadriel, Light of Valinor Alliance Whenever another creature you control enters, choose one that hasn't been chosen this turn Add
Given the relative power of current lifegain mechanics, it seems like we should be able to flip this card into Chalice of Death without too much effort, at which point it becomes a fairly hard-to-remove win condition for the right kind of control decks
If they were suddenly to print a card that was functionally the same or very similar to it, but it only cost 3 mana, then I doubt it would hold that price, despite limited supply