When Shen is played as a reaction during a chain, does his Shield ability trigger and go on the chain, allowing opponents to react before he gains the additional might?

Ruling: Shield is a passive ability, not a triggered ability, so Shen gains the additional might immediately when he becomes a defender. There is no window to react before he has the bonus.

Nuances:

• "While" and "if" indicate passive abilities that apply immediately
• "When" and "at" indicate triggered abilities that use the chain
• Shield is a keyword with reminder text explaining it means "While I am a defender, I have +X [S]"