Does Mageseeker Warden prevent units from entering ready via Sun Disc?

Ruling: No, Mageseeker Warden does not prevent units from entering ready via Sun Disc. Mageseeker only prevents the action of readying (rotating an exhausted unit to ready), not units that enter the battlefield already in a ready state.

Sequence:

• Units normally enter the battlefield exhausted
• Sun Disc (like Accelerate) causes the unit to enter ready instead
• The unit is never seen as exhausted, so there is no readying action to prevent
• Mageseeker Warden cannot interact with this because no readying occurs

Nuances:

• Readying is specifically defined as the action of rotating a card 90 degrees from exhausted to ready
• Entering ready is not the same as being readied - the unit never transitions from exhausted to ready
• This works the same way as Accelerate, which has explicit rules stating it doesn't interact with abilities affected by units becoming ready
• Sun Disc uses the same functional wording as Accelerate ("enters ready" rather than "ready it")