It is treated as an Xyz Summon, you transfer materials, and that monster is destroyed during your opponents next End Phase
Although there are restrictions on fusion summons and ritual summons in Defense Position, if you want to make it Attack Position, you can activate it during the end phase of the opponent's turn, and I think there will be no problem
It could also increase its strength by sending all other Crystal Beast monsters on the field to the graveyard to gain 1000 ATK, meaning it could gain up to 7000 additional ATK
These field names come straight from the actor's dataset schema, so what you see here is what lands in your dataset
Commander Though Foundations doesn't have any Commander decks, the Starter Collection does include a few cards that aren't Standard-legal
Replenish will make it into the deck