Whenever you cast an instant or sorcery spell from your hand, open an Attraction.
, : Exile target instant or sorcery card with mana value X from your graveyard and choose an Attraction you control that doesn't have a midway counter on it. Put a midway counter on it. For as long as that Attraction is on the battlefield, whenever you visit it, copy the exiled card. You may cast the copy without paying its mana cost.
Myra is a spellslinger commander that turns your instants and sorceries into engine fuel: every spell you cast from hand opens an Attraction, and her activated ability lets you 'reload' Attractions to free-cast copies of spells you've stockpiled in the graveyard whenever you visit them. You play a normal U/R spells.dec, padding it with Attractions in your contraption deck, and grind incremental value off dice rolls until you copy a big spell or burn the table out.
Generates two layers of value per spell — an opened Attraction plus graveyard ammo for later free copies
Free-cast copies via midway counters can repeatedly recur removal, card draw, or burn without paying mana
Strong synergy with cheap cantrips that open Attractions and stock the yard simultaneously
U/R gives access to the best card selection, counterspells, and burn in the format
Attractions/stickers require playing the optional contraption deck, which many tables ban or aren't set up for
Heavily reliant on dice-roll variance to 'visit' Attractions and trigger copies
Engine is slow and grindy with no inherent fast win or protection
Removing Myra shuts off the Attraction-opening trigger entirely
X-cost activation competes for mana with casting spells
A big sorcery worth stocking in the yard so Myra can copy it for a free game-ending recursion.
Maximize dice consistency with Pixie Guide, Barbarian Class, and Krark's Other Thumb so you actually visit Attractions every turn, and tune your spell base toward cheap cantrips that open Attractions while fueling the graveyard. Add high-impact instants/sorceries worth copying for free (counterspells, mass removal, big burn) and protection like Lightning Greaves to keep Myra online. If your table allows it, lean into the strongest Attraction package; otherwise pivot the shell toward a more conventional U/R spellslinger build.
Legendary Creature — Human Performer
, 
: Exile target instant or sorcery card with mana value X from your graveyard and choose an Attraction you control that doesn't have a midway counter on it. Put a midway counter on it. For as long as that Attraction is on the battlefield, whenever you visit it, copy the exiled card. You may cast the copy without paying its mana cost.