Skull
Kill Lukash is a mission featured in S.T.A.L.K.E.R.: Shadow of Chernobyl.
The player can get this mission from Skull once he's done the Kill the tower sniper mission.
Description
We're about to blow up the fence and get the party going. I can see you're a good shooter - maybe you could take care of the tower snipers? With snipers out of the way, we'll have an easier time getting to that spaz Lukash. Step aside, will you? We need to get ready...
― Skull
Completing the mission
Unlike most missions in which you have to kill or protect someone, you don't immediately fail the mission if Skull dies, because there will be another Duty member back at the farmstead to give you your reward upon killing Lukash and his exoskeleton-wearing bodyguard (equipped with TRs 301, Chaser 13, GP 37 or any other Freedom weapon).
If you take this and the other quest Skull gives you, Freedom will remain hostile to you for the duration of the game, while Duty becomes friendly (despite General Voronin tellling you that Silence, Skull's group, is a splinter group and not Duty).
Also, taking on the quest from General Voronin to get a Bulldog-6 will be more difficult as eveyone inside the Freedom Base will respawn and attack you on sight, and Chef may be killed by the Duty assault, though the Bulldog-6 is still in the armory. To counter this, it may be wise to obtain the weapon and store it elsewhere after the raid is complete.
Reward
The reward is a lump sum of 8000 RU, but you get the rights to freely plunder the Freedom base and its armory.