A mitigation block is an order-block-style zone that price returns to so that participants caught offside in the prior move can “mitigate” — reduce or exit — their losing positions near breakeven, with the retest expected to push price away again. It is the last up or down candle before an impulsive move, marked as a reaction zone, framed by the narrative of trapped traders managing risk.
In smart-money terminology a mitigation block and a breaker block are close cousins and the labels are used inconsistently: many traders distinguish them by whether the origin took out a prior swing (often called a breaker) or did not (often called a mitigation block), while others use the terms interchangeably. The shared idea is a revisited origin of a strong move acting as support or resistance.
Because the term sits on top of order-block and structure definitions that already vary, “mitigation block” means whatever the specific teacher’s rules say. Definitions vary, so the only honest way to evaluate one is to fix the exact qualifying conditions — what move, what swing interaction, what invalidation — and backtest that precise version.