For starters, only one monster can be normally summoned per turn, meaning that unless the player begins their turn with the means to special summon included in their hand, the Synchro summon would take at least two turns
Your opponent can't activate Spell or Trap cards in response to this effect's activation, either
Adrestia Aetherwing, Golden-Scale Flagship Arcee, Acrobatic Coupe Balamb Garden, Airborne Bessie, the Doctor's Roadster Blitzwing, Adaptive Assailant Cyclonus, Cybertronian Fighter Damocles Base, Sword of Kang Esika's Chariot Flamewar, Streetwise Operative Goldbug, Scrappy Scout Golden Argosy Grond, the Gatebreaker Heart of Kiran Jackdaw Jetfire, Air Guardian Megatron, Destructive Force Optimus Prime, Autobot Leader Parhelion II Prowl, Pursuit Vehicle RMS Titanic Ratchet, Rescue Racer Shorikai, Genesis Engine Skysovereign, Consul Flagship Slicer, High-Speed Antagonist Starscream, Seeker Leader The Belligerent The Falcon, Airship Restored The Fantasticar The Fire Nation Drill The Indomitable The Last Ride The Lunar Whale The Omenkeel The Prima Vista The Prydwen, Steel Flagship The Regalia The Thanos-Copter Ultra Magnus, Armored Carrier Valor's Flagship Weatherlight Weatherlight Compleated
Released in the spring, Ikoria: Lair of Behemoths introduced the ability for players to combine cards together to create monsters using the mutate keyword
