Diagonal arrows adds two additional arrows firing diagonally. Diagonal arrows can be chosen more then once. Diagonal arrows act as normal arrows with 100% damage and the ability to crit. Additionally diagonal arrows are affected by multi shot, blaze, bounce, etc.
Due to the lack of damage reduction with diagonal arrows (as opposed to front arrow), if running staff, avoid getting front arrow, stack multiple diagonal arrows. This is one of the few occasions when stacking more than one instance of multishot yields a substantial boost in damage. (somebody please test specifics, It's clear this produces substantially higher damage, but I'm not experience enough to get specific numbers.)
This can be OP.