All hail our crab turtle aetherborn god overlords
Number One I've been playing with squirrels a long, long time, and no card has won me more matches in those decks than Squirrel Wrangler
You must then build a 100 card deck (including the Commander), but with a couple caveats: You may have no more than 1 copy of a given card in your deck (excluding basic lands) All cards in your deck must only contain mana symbols and colors matching your commanders color identity The Commander rules committee already has a rules document that clarifies all the specifics for how to play, so I wont bore you with any further rehashing here
As for countermagic, saying no is another incredible move to make
Proliferate with Ichormoon Gauntlet and Flux Channeler to get more activations of Narsets minus ability
Shes getting play in basically everything that can support her, and has recently even been compared to Elspeth, Suns Champion