If an opponent reacts to Shen being played onto Trifarian War Camp with Gust (which targets units with 3 or less Might), can Gust target Shen, or does Trifarian War Camp's +1 Might apply instantly?

Ruling: You cannot react to a permanent (unit/gear/add ability) being played. When a permanent is placed on the chain and finalizes, it automatically resolves immediately before any player can react to it. Therefore, Shen would already be on the battlefield with the +1 Might from Trifarian War Camp before Gust could be played, making Shen an invalid target for Gust.

Sequence:

• Shen is played as a reaction and goes onto the chain
• Shen finalizes (almost always immediately after going onto the chain as pending)
• Shen automatically resolves and enters the battlefield
• Trifarian War Camp's +1 Might applies to Shen
• Only now can opponents react with spells
• Gust cannot target Shen because he now has 4 Might

Nuances:

• Action and reaction speeds don't change the type of card, just when it can be played
• Once a unit is on the chain, it behaves the same way regardless of what speed it was played at
• When You Play Me (WYPM) triggered abilities do go onto the chain normally after the unit resolves and can be reacted to
• You cannot finalize a card while another is resolving