PoB: https://pobb.in/_NxXuf0c_C8p (this is already with Merc configured as a party member)

Merc PoB: https://pobb.in/0-164XohzWbK

Just exploring a fun concept I saw from /u/dotasopher last league using Oath of Winter to freeze everything offscreen on a Spark build. Made the build 2 weeks ago but never got around to showcasing it.

In terms of coverage, Spark can potentially rival Kinetic Blast and Tornado Shot if the caster has enough cast speed, projectile speed, duration and pierce. An easy way to do that this league is by using RF of Arcane Devotion which now grants more cast speed, Widowhail for projectile speed and corrupted Mageblood + duration on the tree. With this level of coverage and Oath of Winter + Three Dragons, I can freeze offscreen pretty reliably even on targets with a lot of health or mitigation. This keeps me and my Merc very safe even in very juiced maps.

On the off chance that I do encounter unfrozen enemies, I have a 1-hit defence layer with Kintsugi + Wind Dancer + Wind Ward + Flesh and Stone on nearby enemies and a decent amount of avoidance with 90% evade and 75% spell dodge. This usually buys me enough time to freeze them before they get another hit in. Not the most reliable defence I'll admit, but I die a lot less than I thought I would (frankly speaking, I die mostly due to DoTs).