The system exists because the Pokmon Trading Card Game grew far bigger than anyone expected
His abilities are all about Cats, pumping up your Cats with +1/+1 counters, making Cat tokens and dealing damage based on the number of Cats you control
Sometimes, you'll be forced to make your move and have to simply hope that the opponent doesn't have interaction
Other than that, something that can tap a creature the turn it comes into play can help build your Well Rested counters the turn after it comes into play rather than two turns later
The strength of Wrenn and Six lies in its +1 ability, which returns a land from your graveyard to your hand
Unfortunately, this cant really find you any other true modular creatures (the only other Construct with the ability is Arcbound Worker), but it will find you modular-adjacent support pieces, like Steel Overseer, Iron Apprentice, and Hangarback Walker