Moritte of the Frost | Staff of Eden, Vault's Key | Kappa Cannoneer

Cards

({2} magic symbol) ({G} magic symbol) ({U} magic symbol) ({U} magic symbol) plus enough mana to pay for commander tax, if applicable available.

Cast
Moritte of the Frost from your hand or from the command zone by paying ({2} magic symbol) ({G} magic symbol) ({U} magic symbol) ({U} magic symbol) plus commander tax, if applicable, choosing to have it enter the battlefield as a copy of
Staff of Eden.
Put
Moritte of the Frost into your graveyard due to the legend rule.
Morrite of the Frost's enters-the-battlefield ability and
Kappa Cannoneer trigger.
Resolve the
Kappa Cannoneer trigger, putting a +1/+1 counter on it and causing it to be unblockable this turn.
Resolve the
Moritte of the Frost trigger, returning
Moritte of the Frost from your graveyard to the battlefield as a copy of
Staff of Eden.
Repeat from step 2.