cinnamoroll card sleeves Melffy of the Sea Yu-Gi-Oh! Holographic – Kado Supplies Product Material Loungefly Sanrio Cinnamoroll Balloons Cardholder

It introduces Synchro Summoning, which becomes the main focus of the duels

This expansion also adds the Poke Ball and Master Ball Holofoil variants, which (for better or worse) effectively triples the amount of Holofoil cards to collect

(You can only gain this effect once per turn.) If this card is in your GY and your opponent controls no cards in their Spell & Trap Zone: You can Special Summon this card in Defense Position, but banish it when it leaves the field, also you cannot Special Summon monsters for the rest of this turn, except Winged Beast monsters

Looking on the type line, we can see that he's a creature, and his specific creature type is "Troll Shaman"

Yu-Gi-Oh!: Millennium World