The opponent is casting Duress
Depending on where you plan to sell bulk Pokmon cards, you might need to adhere to specific rules, such as each pile having X amount of cards or each pile must have X amount of commons, uncommons, and rares
Shaun's last ability will exile all Synth tokens you control, not just Synth tokens created by its first ability
(10/1/2005) The player chooses modes, pays additional costs, chooses targets, and so on for the copies when casting them
It's a solid inclusion in Dinosaur Tribal decks like Gishath, Sun's Avatar, it's an undercosted 7/7 so it's great in Ghalta, Primal Hunger, and it has a whopping 12 mana cost so it's great in CMC Matters decks that run stuff like Nissa's Revelation