Encase is a CC skill that doesn't do any dmg by default (unless you chose to morph into Shattering Prison), but this skill have a place on very niche builds, specially due to its high magicka cost that makes it not viable on pve, and somewhat viable for pvp for like 1:1000 sorcs.
For pve you don't really need that CC, and the dmg morph doesn't compensate since
it does less dps than Soul Trap, while costing a lot more to use (2x Shattering Prison = 8102 magicka cost, 1654 total dmg / 1x Soul Splitting trap = 2700 magicka cost and 1692 total dmg), you can't dmg bosses with Shattering Prison, and for pvp you will spam 3 of these and see yourself consuming a lot of your magicka pool.
It's a very expensive ability to spam, and it does no damage.
There are multiple ways to remove it. There's 4 abilities that make you completely immune to it, (which means the sorc used a LOT of magicka with no effect) with one ability (forward momentum) you can use every 8 seconds (if you wish) and never get rooted again.
The fact that it applies an effect or a dmg
after the ability is over, makes it worse.
My fix:
When you cast encase, you see a purple aura going forward, whoever is affected by that wave, get a Dot debuff that lasts like 10s or something damaging X by each second, making it viable for Dot based builds.
Descrease its cost to 2750 magicka due to facility of missing (even on pve, you have to cast it multiple times to affect every mob) and it's not a grounded DoT like liquid lightning or wall of elements.Snare or root should be a morph choice, maybe tied with a 10~20% chance of proccing for each thick of dmg since it's now a DoT, this snare or root tied to a chance of proccing, won't make this ability OP on pvp