Originally Posted by Zenithale

That's not the first time I read that, and honestly I don't understand why there are so many people saying Cannon stage ability is useless/bad. Sure, it depend entirely on the map: if there is no cannon that's useless, indeed. But note on map with cannons the ability affect ALL your 5 Teams and is additive (1 ability = 2 shoots, 2 abilities = 3 shoots etc). Much more efficient than a flat +x% Attack/Defense, especially for beginners who don't have 4 strong Teams. Even a weak Team can kill a stronger Boss who has already lost X0% of its Life.
IMO the only completely useless abilities are the [Raid Boss] ones, because Raid Boss are weak and we prefer to poke (more or less hard) them most of the time (else we share them to random players and they will kill them for us very quickly).

As you say, it's not useless but the fact is it's fair to say it's bad due to the rarity of said cannons. It's a niche ability that rarely comes up, and unless your teams are weak (as you mentioned beginners), it makes little difference as your teams can clear maps without too much issue already. It's useful for newbie teams on event maps with cannons, but that's about it.

RB Buffs are silly 99% of the time since the only time they're useful is the super-rare spawned RB events. RB events are probably rarer than stages with cannons and considering the rare spawn is the only one where those buffs could actually mean the difference between killing them or not, their usefulness is damn near 0.

Cannon ability is bad because cannon are rare (like what... 3 or 4 event with cannons? Idk if fireworks nodes count as cannon or not), it only add a target to to cannon (it will be interesting if it was a cannon damage boost but not) and anyway, most of the time, there is not that much ennemies remaning when a squad pass through a cannon node.
But if it affect all the squads and not only the one with the girl, it's less bad than expected. Fortunatly, thoses girls also have a +10% damage for whole team and respectivly a whole target and 2 target skill. It could be worse.

I just have reacted about Cannon ability because there are in fact a lot of other abilities as bad as it. For example, when you use Autorun to do something else at the same time ALL Solar Blast abilities are completely useless (+X% Shine cristals drop rate, +X Sun Nodes, +X% to Solar Blast). On maps without any Pest Nest several other abilities are completely useless (-50% Damage, Change them in Recovery Node when you walk on them); the same when there are not any Recovery Node (x2 or x3 Recovery)....

So, just to say there are a lot of other abilities who are more or less often useless. Cannon ability is bad, sure, but IMO it's certainly not the worst, by far (and Gardenia is a real beauty but that's not the question). Anyway I don't take the point of view of a veteran player with a full Set of 5*/6* maxed (20+ Knights), because in that case you can consider almost all abilities become useless anyway.

- - - Updated - - -

Oh, and yes, the Cannon ability works with Fireworks as well, and is given to all your Squads.

- - - Updated - - -

In fact Cannon ability seems even better than expected, or there is a tiny bug. I have one team with Gardenia (the only one I have with this Ability) and a Helper without this Ability, and when I farm the Reissue #8 mission 8 all the Teams trigger 2 shots (as expected) but my Team with Gardenia triggers 3 shots!