Octobrush with Burst Bomb and either Zipcaster or Triple Splashdown.
Burst is everything octobrush needs. Octobrush has a very noticeable lack of range compared to other weapons. The very fast nature of the weapon means that slower bombs (cough suction bomb cough) cannot even function as a ranged option on the weapon, but burst bomb is an immediate, on demand ranged option. It is everything I want, I don't care if got slider to go with it. As for the specials, Zipcaster already works very well on it, enabling it to flank & position in a game with otherwise very limiting map design. TSD, on the other hand, serves a wholly different function. It enables sharking on a whole different level, and can protect you or trade kills in certain situations. But burst bomb it the more important part by far.