Recently there was a change on the Global Lab and then KR that added gear caps to Mediah and Valencia siege (and also removed Balenos and Serendia temporarily). This change is the latest in a long line of changes where PA has completely ignored/forgotten that Shais exist and will make it impossible to play a Shai in siege (except for the still uncapped Calpheon).

The design of the class forces it to only have one viable gearing option for endgame pvp, stacking DP, since it's unable to do viable damage and must get by by staying alive long enough to provide enough buffs/debuffs/heals/cc to offset the complete lack of damage. Shai doesn't really have inherent tankiness besides its large hp pool, so forcing them to abide by the same DP caps as all of the damage dealers means that shai will be unable to fulfill its one role.

For comparison, here are the new DP caps for Mediah and Valencia siege as well as my current stats from the new stats window. You'll see that I'm 467 over the evasion cap and 119 over the DR cap for Valencia, but I'm 264 under the AP cap. That's a major major problem. Shai is not capable of just going hybrid and picking up more AP to contribute that way. 

If something isn't done about these caps with regards to Shai, then it will be the deadest that a class has ever been in siege. Sure, some classes have performed poorly compared to other classes in the same role leading to few of them being present, but they still at least had a role and weren't a completely dead spot. Bubble was also one of the biggest reasons to bring shais, but novas getting a wall (which is also on a much shorter cd, 2mins vs 5mins) while also still being able to provide good damage has severely diminished the importance of bubble.

I can think of several ways that this can be addressed. First, would be to make the caps class specific. The goal of the caps seems to be to put damage dealers around the area of 270 AP 330 DP unbuffed in order to reach the cap numbers with buffs. Most siege guilds these days have requirements and most of their players anywhere from 5-15% above those numbers with a few outliers. Now, I'm a bit of an outlier when it comes to shai, but typically a siege geared shai will have somewhere between 500-520 DP. An appropriate cap for shai would be roughly 400 DR and 1100 evasion for Valencia and 380 DR and 1050 evasion for Mediah. You could even set the AP cap at 250 if you're worried about "hybrid shais" somehow dealing damage.

The second way that this could be addressed...give Shai succession which lets it play the damage dealer role. A lot has already been written, particularly by Phelsong, about the large amount of changes that Shai needs in order to address the problems it experiences such as bad damage cones (particularly as the relate to the z axis), slow movement, unprotected damage skills, and large gaps in skills that are supposed to be fully protected.  And while I hope that all of those get addressed during the upcoming class reworks (you didn't somehow forget shai again for those, right?), I think that giving shai a succession option should be considered. Shai is already by far the worst grinder at Elvia spots (I can get literally twice as much trash/hr at orcs using my tagged mystic and mystic isn't even the best), so having succession skills get some additional pve damage would be welcome there as well. To make it able to pvp though, it really needs additional super armor (possibly have hop give 1s of lingering SA) as well as at least one more CC (some skills already have pve "knockback", but knockbacks are generally awful for pvp so simply making them pvp knockbacks wouldn't work). For prime skills that it can take from the talent, make it similar to witch/wiz where they have options but get locked out of the others, so shai could take one of the attack skills (Forest's Echo, Sun's Fury, or Earth's Tremble) and one buff skill (Shout to the Sky, Summer Rain, Time to Shine, or Sun, Moon, Stars). The debuff skills and full slate of buff and attack skills staying exclusive to talent users (which really really should just be treated like any other awakening weapon at this point) would be appropriate.

Anyway, those are just my thoughts on how the issue can be addressed, but it must be addressed or Shai will be completely dead for siege.

Shai have insane buff that have a realy good impact in any high scale fight,

I am more fan of increasing your support ability that arbitrary wierd Passive
if the shai is to be buff seen are unable to play full dp so be at full potency. so just that these buffs get more impactful.

I propose to increase the effect of every buff and Debuff x2.

3000 HP buff, 
35% atk/cast/movement speed buff(Pen sol),
80% All resistance buff. 
9% BSR every 10 sec.
-35% DR/Eva
-100% Crit chance - 52 AP
Tuning 300 hp recover.

Over Here !.  Duration increase to 15 sec !
DO IT BETTER !!!
+60 AP

+120 DR
+20% Special Attack Damage

and the last of thing GET WELL 200% BSR !!
+50% DR rate for 30 sec !

Should be enough to get a good PVE buff.
And as a bonus you become an S tier above Wizard / witch / Sage class. Completely mandatory in node war and Conquest.

Elin Master Race. The Shai prevail ! The Shai would become the EMPEROR of the Imperative.