Does Mageseeker Warden prevent cards with 'I enter ready' (like Master Yi and Warwick) from entering ready?

Ruling: Mageseeker Warden does not prevent units with "I enter ready" from entering ready. These units come into play already readied rather than readying while on board.

Nuances:

• Mageseeker Warden's "can't ready" only prevents the transition from exhausted to ready for units already on board
• "I enter ready" abilities apply before the unit is on the board
• This same logic means Mageseeker doesn't counter effects like Magma Wurm's ability or Accelerate
• Mageseeker only affects effects that explicitly untap an exhausted unit (like Mistfall, Wallop, First Mate)