Boost Up
See where it says "Set Bonus"? I believe that it's a Proc from a set that you have slotted into one of your powers.
With I16, Procs now have a little icon show up when they fire.

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I'm sure someone will correct me if I'm wrong, but I think this might be something from an IO set? I've been getting it like crazy on my level 50 who is IO'd out. I haven't noticed it on any toons that don't have some sets.
Hopefully someone can, shed some light. I'm curious as well.

We'll see....
Guessing you have the Gaussian build up proc slotted in Tactical Training: Leadership or the Decimation build up proc in one of your single-target ranged attacks.
[Boost Up] is the power attributed to the "chance for build up" IOs in the GSFC and Decimation sets. There was never any visual indication of the power firing, so you'd have to be monitoring your combat logs or combat attributes. Now the icon pops up whenever the proc fires so you at least have a visual indication. Wish the icon were different but it uses the same generic icon all set bonuses use so I guess there's no changing that.
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Ahh, neat, I had no idea they put that icon in or anything, nice to know. Thanks a bunch folks. I had only seen it since logging in post-I16 of course, so no wonder I was confused why Quickness icons kept appearing.
Enemy Resistances - Damage, Mez and Defense
Enemy XP Mods
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Got this flashing regularly for a few seconds at a time while playing yesterday. Teammate never received it. I was on a Soldier of Arachnos (bane) and he on a Brute. It was not syncing up with anything like my card fortune wearing off, or using a power, or anything. It was both in missions and outdoors in Grandville. I do not appear to have had it actually buff any powers of mine when it flashed during battle but I am not positive about this. It would flash up long enough, though, for me to notice and get its info. I was too busy macing things to death to notice how often it flashed, in case it was regularly cycling.
???
Enemy Resistances - Damage, Mez and Defense
Enemy XP Mods
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