Envisioned are immune to drop assassinations, sliding kills, and stealth attacks. It is impossible to eliminate Envisioned non-lethally. ... A fully charged voltaic shot or electrical burst to the head will bring Envisioned to their knees instantly.

Does killing matter in dishonored death of the outsider?

The true major component to the endings is how you deal with the Outsider. You can find and kill him, or use an alternate method. Instead of killing the Outsider, you can take away all his power and make him mortal again.

How do I get to the ritual hold?

The Ritual Hold is accessed by a portal from the top of a stone staircase that has appeared near the entrance to Shindaerey North Quarry. The area just inside the gate is patrolled by two Envisioned. The hold can be stealthily accessed from a ledge overlooking the area.