"Paint the target" New sniper ability for Ultramodern5

Inspired by the Tau from Warhammer 40k I thought this might be a good ability for a sniper to have. If you had two, one could be a spotter allowing the second to take full advantage of this ability as well as the rest of the team. This is intended for sci-fi settings mainly.

Paint the target
Marksman cost: 4
Instead of doing damage the sniper instead paints (marks) the target. This mark is compatible with smart weapons and advanced targeting systems. Once marked the target stays marked until the end of the snipers next turn.

Marked targets get no AC benefit from light cover or cover from obstructed view. And shooters get no penalties for low light. If the marked target is in plain sight attacks gain advantage. This applies to all attacks that can take advantage of the snipers mark.

Lich servants (Grave servitors)

These servants of the Lich Lords are not fully dead, yet not fully alive either. Held between worlds, these once mortal beings are Lich bound for eternity.

Medium Humanoid/undead, any evil alignment (usually that of their master)

AC: 15 (Natural)
HP: 50
SPD: 30ft.
CR: 4 (1,200 exp)

Str: 13 +1
Dex: 14 +2
Con: 16 + 3
Int: 11 +0
Wis: 14 +2
Cha: 13 +1

Damage resistance: cold, lightning, necrotic, and poison. Bludgeoning, piercing, and slashing from non magical weapons.
Condition immunity: Charmed, exhausted, frightened, paralyzed, and poisoned.
Saving throws: Con+8, Dex+6, Wis+3
Passive perception: 16, truesight 60'

The servitor of a Lich lord always carry a wraith blade, usually a long sword but can be anything from a dagger to a great sword. Any attack with a wraith blade that hits on a natural 16+ does an additional (10) 3d6 cold damage. And must make a DC 10 Con save or be paralyzed for one minute. The target can attempt a saving throw at the end of each of its turns to end this effect.