It's quite good that the cost of the skill has been lowered a bit, but in PVE the skill is often still useless, mainly due to the fact that the world is inhabited with quite a lot of monsters that are Immune to Immobilize. Using the skill on those has no effect whatsoever, and is a total waste of magicka.

Suggestion:

• Add a small "Damage over time" component to the Encase. That way it will still be somewhat useful against foes immune to Immobilize.
• Change the skill so that at least the the rather weak explosion on the morph 'Shattering Prison' will take place on enemies immune to immobilize. That way it will not be a total waste of Magicka, and a small part of the skill is still effective.
• Add the "Damage over time" component to the morph 'Restraining Prison' as well, to be somewhat useful to enemies immune to immobilize and snare.

Skill is quite useful in many cases but not against certain type of foes which renders this skill completely useless. A cast against those foes will have no effect at all. Zero immobalize, snare, and Zero benefit from other dark magic passives for a quite high mana cost. Please change it so that it will still be useful but less effective some way.

The small damage over time component even though small, will at least make the skill a little bit more useful because of other passives in the Dark Magic tree like 'Blood Magic' and/or 'Exploitation'- which i think should be changed back to it's original state since it's not consistent with other buffs, that are all applied in an active way as part of an active skill.