If you cast a copy of an instant or sorcery card (for example, one created by Mnemonic Deluge), and the spell is returned to its owner's hand, it will cease to exist. You won't be able to cast it again.
Krark, the Thumbless
Krark's ability triggers at the same time as any other abilities that say "When you cast this spell" or similar, including cascade. Those abilities may be put on the stack in any order. Those triggered abilities are unaffected by the original spell being returned to hand, countered, or otherwise removed from the stack.
The copy from winning the flip is created on the stack, so it's not "cast." Abilities that trigger when a player casts a spell won't trigger.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Mathias Kollros
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
