I've seen this happen many times and wonder, how am I boosting off resist? This has happened to me lots of times in PvP when I pierce someone's resist, always had me wondering. Me and a friend tested this in a 1v1 and came up with... If piercing resist is involved when a spell is casted and there's 1% resist leftover then the game will display the word 'boost' instead of 'resist' on the target. I do not believe you actually get any kind of "boost" when this happens, it's just a graphical glitch.
