History of Surges

Surges are elemental activity modifiers in Tomb of Elders. An elemental Surge gives a 25 percent damage bonus when you use weapons or abilities of the matching element, so players bring matching loadouts. Activity modifiers such as Surges stay active for the whole activity, while per-encounter combat modifiers like Grounded reset when each encounter is completed.

The description comes from a guide written for Episode: Revenant (Act 2) in November 2024, so the modifiers may have changed in later updates.