As of the release of Nature Incarnate, this primarily matters in three cases:
- When "Far-Flung Herds" (The Habsburg Monarchy Livestock Colony Level 6) checks for adjacent Towns in Ravage, it only counts participating Towns.
- The threshold of "Instruments of their Own Ruin" can't make Ravaging Invaders deal Damage to adjacent Invaders that aren't participating in Ravage.
- The Event "Network of Support and Trade" only scales its Defend with adjacent Dahan that are participating in Ravage.
In the rather unusual case where you check if a piece is participating in Ravage for the purpose of one of the above modifiers and then that piece ends up in the Ravaging land mid-Ravage, it continues to either participate or not participate – whichever you originally determined – since participation (or lack thereof)
lasts for the entire Ravage Action.