Dont know if this applies to the other morph toxic barrage.
When you kill someone with Ballista you dont get credit for the kill unless you did dmg to them with other abilities such as poison inj etc. If you kill someone in cyrodiil or imperial city with the ultimate you dont get ultimate back with Combat Frenzy passive or any of their currently carried telvar stones. If you cast minor berserk on yourself you dont gain a dmg increase on bow ultimate (atleast not on tooltip)
PC EU
PvP only