If I play a unit with a 'When you play me' effect that increases my XP to meet a Legend's Level threshold granting 'Your units enter ready,' does that unit enter ready?

Ruling: No. The unit enters the battlefield exhausted (the default state) because the XP gain has not yet occurred when the unit enters play.

Sequence:

• You play the unit while below the Level threshold
• The unit finalizes and enters the battlefield (still below threshold, so it enters exhausted)
• The 'When you play me' triggered ability is placed on the chain as a pending item
• The ability resolves, granting XP and activating the Legend's Level ability
• The Level ability does not retroactively ready units already on the battlefield

Nuances:

• Play Effects are triggered abilities that become pending items after the permanent enters the board, not before.
• A unit cannot benefit from state-based passive abilities that its own play effect activates.