Neutral.
Event. Cost: 0.

Reaction: After you win a challenge by 5 or more STR as the attacking player, kneel your faction card. Then, you may initiate an additional challenge of that type this phase.

Darek Zabrocki
Tyrion's Chain #118.

Link: Decklists

Relentless Assault
Reviews

Rules FAQ:

  • When dealing with effects that permit initiating additional challenges, figure out how many challenges of a given type you're permitted to initiate, and how many challenges of that type you have already initiated.

  • Kneeling your faction is not a cost here, but a part of the effect (there is no "do X to do Y" format used in this card's wording). If this event is cancelled, your faction card remains standing, and you may immediately play another Relentless Assault, if able.
mplain 202
When playing the Sneak Attack plot, does Relentless Assault allow a second challenge? — Statusunquo 1