
Oh look, here's a picture contradicting your "proof" of invoker dominating BSQ.
I'll point it out as it could be unclear, left side has more invokers than the right but yet they still lost by a large margin. I guess having a team of more invokers than the other side does not guaranteed victory.
I never said it was a guaranteed victory if you have more Invokers. I just said that Invoker was the most used class in BSQ because it's by far the strongest.
Since the top scoring classes on the winning side is sorcerer, should we start nerfing sorcerer? lol. Main point is, you can't show a picture and say here's proof of something when that's one scenario and each scenario consists of different people with different skill levels playing those classes.
The majority-of-Invokers-scenario is not unusual, if you play 80+ BSQ you should know it.
Invokers already received multiple nerfs and magnet abuse is hardly a problem when the cooldown has been increased quite high compared to what it was originally. Have you ever played a mana-hungry class like invoker and walk into the AoE circle of a mana burn by a summoner?......................Instant MP consumables takes time to farm so the user actually has to spend effort to get them instead of walking up to the NPC and dropping a few gold to get a stack.
So if something is OP but you need to farm for it, it's okay ?
Invokers got nerfed quite a bit and they are much easier to kill now. There was a time when invokers had full capabilities in BSQ with maxed defense, maxed element resists(before element balancing), instant heals, emergency exit, magnets with lower cd and working at 100%
Invokers being nerfed in the past doesn't mean they are balanced yet.
You may say "lets nerf heals altogether in BSQ". Why not just ban mages altogether, that'll solve all your balancing problems with mages. 
Slowheal cannot outheal a team that's dpsing hard on a locked target. If your team actually has any cooperation, a caught mage will die quite easily. If the mage doesn't die, it's either gear setup, conflicting elements, no teamwork, other side has better cooperation, or you're trying to 1v1 the flag holder (god knows why, bad teammates probably).
A team without enough Magicians / Summoners won't be able to out-control an only Magicians / Summoners team.
*waiting for someone to argue that both teams consists of summoners/invokers/sorcerers*
Thanks for waiting. Both teams consist of Magicians / Summoners, because they are the best classes at CC / DPS / Surviving. Which means the best way to counter a Magicians / Summoners team is to have a Magicians / Summoners team.
Each class has specific roles to play in a group pvp and if the player does not know their role and how to use their class, it becomes less effective.
Ie. archers and ninjas launching everything. The learning curve just happens to be quite low initially for these 3 classes.
Nobody can launch an enemy in the air because it would mean less damages from Magicians / Summoners. We are in a meta in which everyone has to adapt their gameplay to the OP classes.
In your screenshot I see that you're using a pathfinder, just so you know, a pathfinder can infinite lock down the flag holder. But if you're trying to DPS instead of support cc/lock and then the enemy flag holder, well that's all on you.
Yes, Sentinels can lock someone to death easily. Can it lock a crowd to death such as Magicians / Summoners ?
Finally, instead of always looking at stuff to nerf nerf nerf, maybe other classes could use some buffs so they're more fun to play.
With the current situation the Staff can't create active spells. So the best way to balance the classes for now is to nerf the OP classes.
The classes all have different learning curves by the way. "That time when Pallies and Ninjas dominated BSQ". Also it feels a hell lot more rewarding to have the odds stacked against you and win but maybe you want those easy wins.
I don't want any easy win as I don't want others to have easy wins.