Do you have to pay extra cost on Guards! before playing Sand Soldier to have it ready?

To determine if you must pay an extra cost on Guards! to have the Sand Soldier enter play ready, it is important to clarify that you do not have to pay the [C] (Calm power) cost to "have the Sand Soldier ready" upon playing the card. The Sand Soldier enters play as a standard unit, and the option to pay [C] is a distinct, optional instruction that occurs during the resolution of the spell.

Timing and Chain Sequence

When you play Guards! from its hidden position:

1. Play Phase: You play the Guards! spell, and it enters the chain.
2. Resolution: The spell resolves.
   • Step A: The first instruction is executed: "Play a 2 [S] Sand Soldier unit token." The token enters play.
   • Step B: The second instruction is executed: "Then do this: You may pay [C] to ready it."
3. Cost within instructions: As part of the resolution of the spell, you are presented with the choice to pay [C] to ready the unit. This payment is not a prerequisite to play the card or the token, but rather an optional effect to modify the state of the token upon resolution. If you choose not to pay [C], the unit remains on the board in its current state.

Note: I could not fully verify this ruling against the retrieved rules.