The key card is present but its support is thin.
Prioritize useful support such as Crustacean Commando or Slithering Cryptid.
With Genghis and Donatello present, a Mutant that makes Mutagen can create several artifact-entry counters before you spend any tokens.
Your deck already enables the plan but is losing the early turns.
Take a castable early creature or efficient answer before a second expensive payoff.
Mutagen activation is sorcery speed. Make the creature large enough before combat rather than planning to surprise a blocker.
The support is missing
Favor independently useful creatures and interaction if the narrow support does not arrive.