Seeker is a good pick for next 60, sure - but you should improve your dungeon teams, especially Spider, before you start focusing on Faction Wars. You should still be able to proceed some levels further by just hitting enough AOEs with Kael and Ninja plus Armiger to keep the Spider's TM down and some support. After that, you're probably going to need AOE HP burn and/or more Max HP damage. 

Your Kael's build would be good if he had an accuracy banner, but looks like he doesn't - or he does but you have basically zero accuracy on any other gear. Not sure which. Anyhow, he has nice damage and speed, but with only 140 accuracy, he won't be putting many poisons on higher level dungeon bosses, which is also a big part of his job. Great Hall bonuses on magic accuracy might help, but not enough (not in the short term, anyway) as you'd need to reach above 200. 

As for Scyl, there are really two main paths to take - combining both is quite hard and requires crazy good gear, in addition to fully booking her. Support Scyl or Stunning Scyl, basically - the former focuses more on high HP, defence, resistance and speed, with accuracy a secondary concern (as much for her A1 as her A2) and no books required, while the latter focuses on defence, accuracy, speed and even crit rate/damage as you say, plus needing books on her A2. Up to you which you want to go for - you do have Drath so don't need Support Scyl as much as many others do and Stunning Scyl still has the healing passive even if she's squishier and more likely to be debuffed. 

Don't bother about Scyl's critrate and damage right now. You can increase that stats later on, when you have better gear from farming lvl 20+ dungeons. She doesn't need to crit to land a debuff, unlike champs as Armiger, Peydma and Dhukk, who can do their stuff only with a critical hit. Just focus on the relevant stats def, speed and accuracy. For PvE content, I think even hp is more important for Scyl than crit, she is the reviver and should survive the hard hitting attacks - revivers with low survivability don't help.

Even with mediocre gear it's possible to push all relevant stats if you don't focus on her damage. Look at my Scyl for example: only two items have 6* (helmet and amulett), and look at this ugly uncommen 4* banner. But she is still fast for a non-speedbuffing champ with 195, has 249 accuracy (rule of thumb says dungeonlevel x 10, I need 1 more acc 😺) and enough hp and def to survive a hit in lvl 25 dungeons. Still room for improvement, but she can do her job with that gear.

i

P.S. Does anybody know why they translated "Scyl of the Drakes" into "Draconia" for the german version?

I am thinking gorgorab before seeker

Cheers for the feedback so far.

I've taken crit rate/damage away from Scyl build and she so much better. 50% extra def.  Also working acc and stun into her. Chur.

I was torn with Seeker and Gorgorab but I figured Seeker has shorter turnaround and I already have reviver outside of FW. @Trips, you helped last time and Armiger was a good shout, so chur. Why you say Gorgorab?

Infact, I'm sure you've all helped me before. So chur if I'm correct

Also @L9753, I have acc banner and zero acc elsewhere. Can't keep him in lifesteal without sacraficing Acc or everything else