Surprise Attack
From Eldfall Chronicles
An Attack with this Trait halves the target model’s OFF, DEF, ACC, AG, and INT until the end of the Activation Sequence.
Community Answers (Discord)
Q: Does a Sentinel with Vigilance see in all directions and resist Surprise Attack?
A: Yes — Vigilance grants 360° awareness and immunity to Surprise Attack, and it keeps STK 2 on reactive shots. To shut it down, engage it in melee first so it can't make ranged attacks and its LoS is limited to its Awareness. (— meksmaks)