You are making a big mistake there. Those three stooges didn't kill the MC simply and quickly. Instead they kicked him around, made him suffer emotionally by describing how they slaughtered the orcs and raped+murdered the elf. Then made him "fly" down the cliff, not even bothering to check the corpse. Now, just look at what happened to them: they are all dead and the MC is alive.
If the MC tried to come up with fancy, slow ways to kill them, it only means giving them time and opportunities to escape or strike back.
The Evil Overlord List has a number of points related to this, for example:
- Shooting is not too good for my enemies.
- I will not gloat over my enemies' predicament before killing them.
- When I've captured my adversary and he says, "Look, before you kill me, will you at least tell me what this is all about?" I'll say, "No." and shoot him. No, on second thought I'll shoot him then say "No."
- I will be secure in my superiority. Therefore, I will feel no need to prove it by leaving clues in the form of riddles or leaving my weaker enemies alive to show they pose no threat.
- All slain enemies will be cremated, or at least have several rounds of ammunition emptied into them, not left for dead at the bottom of the cliff. The announcement of their deaths, as well as any accompanying celebration, will be deferred until after the aforementioned disposal.
- The hero is not entitled to a last kiss, a last cigarette, or any other form of last request.
- I will never utter the sentence "But before I kill you, there's just one thing I want to know."