Discuss Divinity Original Sin, as well as comments posted to our Divinity Original Sin Wiki and Divinity Original Sin 2 Wiki
 2
 
Guerrila, Hot Head, BackStab, Chameleon Cloak, Thick of the Fight, got low HP + Death Wish, got that combo and dealt 10k HP. As long as you can calculate the damage. This would be insane.
10K hp damage? at which lvl? with X FIN?
Come to think of it, this skill is not as powerful as it seems.
Yes, you get 280% damage for 3ap(chameleon cloak+mortal blow), the special effect [hit enemy(vitality >20%) with this skill and its vitality drops below 20%, the target instantly dies] ignores armor,but it cost 3sp and can only be used once per combat.
For those who don't use scrolls, to max out one turn damage, skin craft(combine with adrenaline&flesh sacrifice) is essential, so if you want to use mortal blow,you will also need apotheosis, which means you get 280% damage for 5ap(apotheosis+chameleon cloak+mortal, a little more than 280% actually as apotheosis give 5 finess),only 30% more damage than two and a half basic attack.
For a 4ap rogue one turn maximum damage(skip the next turn as a result),backlash(85%)+overpower(150%)+adrenaline+flesh sacrifice+crippling blow(115%)+skin craft+adrenaline+flesh sacrifice+overpower+crippling blow deals 615% in total.
Meanwhile Apotheosis+adrenaline+flesh sacrifice+backlash+overpower+skin craft+adrenaline+flesh sacrifice+backlash+chameleon cloak+mortal blow only deals 600% in total.
Yes,like other scoundrel skills, mortal blow can backstab.
BUT in the late game, the base damage of a dagger is about 55% that of Two-Handed(82.5% when duel-wielding. One-handed weapon is about 64%, 96% when duel wielding. Staff, crossbow are only a little less than two-handed, almost the same), meanwhile other class can reach 90% critical chance. For a 22 level character,20% from weapon,15 from 15 attributes in wits(LV22, 45 attributes in total,30 to finess), 10% from hot head,12% from peace of mind, 14% from eternal artifact enchanted necklace with giant flame rune,5% from wits in rings each(10%),5% from wits in trousers, 4% from belts, that's 90% in tota (Although in order to get all these equipment, you need to check out merchants many times).
Look back at scoundrel skills, only 3 vitality-damaging skills' damage/ap ratio is more than 50%/ap(basic attack), while two of them cost 2 or more source. 4 equal to that ratio. 3 less than that. None has hard control effect like knocked down(terrified may count but it's resisted by magic armor and Terrifing Cruelty has the WORSTt damage/ap ratio while costing 3ap).Don't forget dagger has the shortes range and all scoundrel AOE skill damage is a joke compared to magic. They really should think about buffing scoundrel skills.
Return to Mortal Blow. It needs a CD, Less SP COST(Considering dagger's damage, maybe 1sp lIke overpower). (NO ADDING AP COST ******* thank you.)
Mortal Blow is a finisher, not a main damage source, It's mainly used for it's 20% damage execution. For example,Marg the troll has 6048 hp, so it does 280% damage+1209 execution damage and it can be combined with overpowered in the above combination. It costs a lot of memory, however if you look at all scoundrel skills, majority of them either do wrong damage, cost too much AP for the damage they provide and their utility is mild at best. Moral of the story, they aren't worth it compare to normal attacking from raw damage perceptive.On the counter-point: "Aoe damage Scoundrel skills damage is a joke compared to magic", That's not exactly true, because magic schools deal magical damage which means they're subject to resistences where as physical damage will always do the same damage. Fan of Knives can backstab, so it deals 150% damage+Highground damage at minimum and it has pretty low cooldown of 2 with 1 source point cost. You can use Skin Craft to deal a decent one turn burst. Of course, The counter arguement to this statement is Rangers and Necromancery, but these classes have their own problems regarding mobility skills, weapon limitations and skill synergy/conditions. Their source point skills are only redeeming factors for them.
This skill is a rip off.
Tested with Guerilla, does not stack.... This skill is weakers than Daggers Drawn in pure damage