With only 4 darts to use, one of which is only good for goofiness and wont truly trick probably 95% of the playerbase, i think the blowpipe could use a few more additions that while not elevating it to being a go to choice in PvP at all times, does make it have some more uses to consider it in.
Lightningrod Dart: As the name implies, it would not create lightning but rather draw electric based attacks and natural thunderbolts from the storm to the location of the dart. Handy against pirates during a storm or just to keep the lightning away from kegs on your ship when trying to sell them, the dart can only draw one storm strike or 3 electric orb things from the ocean crawlers.
Fog/Blind Dart: Probably would be too op but the dart would 'blind' it's victim or just cloud their vision with fog so it's harder for them to see you from a distance. Given how powerful such a dart would be the effect would have to be very short lived (about 3 seconds), long enough to get some sneaky hits in or just to keep your enemy from hitting you too easily. Maybe a comm/achievement would exist for killing someone while under the effects of a blindness dart?
Sickness Dart: Would cause the target to after a delay, pause movement and vomit. The effect would trigger 2-3 times before wearing off. The brief halting of movement would create opportunities for attacks.
Peace/Pacify Dart: 3-4 seconds of being unable to use weapons when it hits a pirate, in PvE the enemy would just ignore you for that duration. Maybe wouldn't be too broken to have the effect last 10 seconds if hostile actions instantly undo the dart's effect. ((this wouldn't stop ship interactions like bucketing, repairing, anchoring, altering the sails and Cannons would still be useable.))
These darts have been thought of while trying to strike a careful tightrope of not being too broken and also sticking to the theme of being very saboteur/ninja like. I would love to know if these would still be broken as currently imagined, how that could be changed (if possible) or if there is other darts that could exist.
