Moonshaker Cavalry turns a white creature board into a large flying attack. When it enters, your creatures gain flying and +X/+X for the turn, where X is the number of creatures you control. A wide token board can therefore become dramatically larger while gaining evasion, giving white decks a finishing creature that rewards the development they have already completed.
Elspeth, Sun's Champion and other token makers help establish the creature count before the Cavalry arrives. Token doublers can increase that foundation further, while blink effects can reuse the entry trigger on a later turn if the game continues. The Cavalry itself contributes to the creature count when its trigger resolves, provided it remains under your control.
The effect grants flying but not haste. Creatures that entered this turn normally cannot join the attack unless another effect grants haste, so a board made entirely of fresh tokens may need to wait. Existing creatures are the main beneficiaries on the turn you cast the Cavalry, and a deck should prepare them before spending eight mana on the finisher.
The size of the bonus is determined as the entry trigger resolves, making creature removal before that point relevant. Once the bonus is established, later changes to your creature count do not continually recalculate it. Cast the Cavalry when the existing army can exploit the flight and power immediately, and keep a recovery plan in case the first finishing attempt is disrupted.
