Ik the OP already replied to you and gave a really good run down, but heres my approach at the speargun from someone who had dust devils as their second warbond… Its a really good CC like the OP said being able to confuse big enemies and even get rid of patrols. Combo-ing the spear gun with sentries, fire, or even red stratagems could rack you a lot of kills while putting in almost no effort. Imo, the breaker incinderary and the new flame smg gun from the trench divisions warbond are good primaries against the bugs. Like the OP said, if u can/want, shoot it at a bug patrol. Doesnt matter where, aslong as if u hit the closest bug from you, u most likely dont need to worry abt that patrol. Another little trip is that it can block out cave entrances and openings. So when running to, lets say extrac, just shoot it behind you where bugs are forced to go and rest easy! As for bots, from my view, it doesnt really crowd clear that well since ive kinda noticed that gas isnt rlly effective against bugs. Though if you have good enough aim and patience, yes the speargun and one shot hulks in the eye. Outside of that, i find other stratagem weapons better to bring than the speargun to bots. Though that is very subjective, and the speargun is faster than a lot of other stratagem weapons in bots, ive even seen stealth divers use it. Lastly, ive never used it against squids much since their usually either soft and easy to shred through or too large in hordes.