When Magician + Factory are already face-up on the field, if a Shark's (or Rabbit's) effect is activated, both Magician and Factory trigger, and form a chain. The links of this chain are subject to the owner since both effects are optional.
Factory can be chain link 2 and Magician chain link 1. Factory resolves first grabbing a Shark from the deck and then Magician resolves special summoning a monster. Since the last thing was the special summon of the monster, Shark triggers and can summon itself in a new chain after the current one finishes resolving.
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When wind-Up Factory is already face-up on the field and a Magician is summoned, if that triggers a Shark in hand, Shark is special summoned as chain link 1. Then after that Magician and Factory form a SEGOC chain, and they follow the above example.
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If a Factory is face-up on the field and a Magician is summoned, then if Factory searches up a Wind-Up Shark, that Shark's effect cannot be triggered by Magician's summon anymore, since Factory resolves after whatever triggered it has finished resolving. That means that by the time Magician is summoned there is still no Shark in hand, and by the time Shark is added to hand, Magician's summon has already been completed.
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Magician must be face-up on the field when the other Wind-Up monster’s effect activates, when it resolves, and when Wind-Up Magician itself would activate. Magician does not need to remain face-up to resolve, but the last line in its text prevents it from activating if it’s not face-up.
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Wind-Up's rulings by Redshift link here.
Factory can be chain link 2 and Magician chain link 1. Factory resolves first grabbing a Shark from the deck and then Magician resolves special summoning a monster. Since the last thing was the special summon of the monster, Shark triggers and can summon itself in a new chain after the current one finishes resolving.
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When wind-Up Factory is already face-up on the field and a Magician is summoned, if that triggers a Shark in hand, Shark is special summoned as chain link 1. Then after that Magician and Factory form a SEGOC chain, and they follow the above example.
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If a Factory is face-up on the field and a Magician is summoned, then if Factory searches up a Wind-Up Shark, that Shark's effect cannot be triggered by Magician's summon anymore, since Factory resolves after whatever triggered it has finished resolving. That means that by the time Magician is summoned there is still no Shark in hand, and by the time Shark is added to hand, Magician's summon has already been completed.
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Magician must be face-up on the field when the other Wind-Up monster’s effect activates, when it resolves, and when Wind-Up Magician itself would activate. Magician does not need to remain face-up to resolve, but the last line in its text prevents it from activating if it’s not face-up.
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Wind-Up's rulings by Redshift link here.