Question on Dooms LVL Death

How exactly does it work? I dont understand it

Well depending on the enemy's level it does more or less damage. It applies this bonus damage if the target's level is divisible by the multiplier. Example lvl 1 LVL Death will do bonus damage if the enemy is level 6, 12, 18, or 24 whereas lvl 2 LVL Death does bonus damage to targets whose levels are equal to 5, 10, 15, 20, 25. It will deal the skills base damage depending on level and if you do proc the bonus damage then it removes 20% of the enemy's health pool.

ok i understand now thanks!

i wish volvo would implement on the top bar the each enemies mana pool and their lvl

Glad I helped, but that won't happen, in Dota you're expected to left click on people to figure out their items, level, and mana. Its just a mechanic that is left out to allow surprises and make you think before committing to a fight.

Just a little more info, that nuke also deal bonus damage at level 25 in addition to level multiplier.
This is important because suddenly Doom's nuke is getting good again after late game.