I would say OK murder would be Rattus Rattus (sets you up for a bank robbery), Milano Calzone and Don Barlone (they occupy the Trynnie's Sixth Bough), Crock (get all you need from him, then whack him, to prevent a kidnapping, and get access to his chest). Four scumbags that deserve to die.

Rapax King is a rapist so i'm fine with his death... the kings son is just like his dad so i'm okey with ending him as well

The old trick of making up reasons out of thin air to excuse one's own misbehavior.
Rapax king is accused of rape without any indication of this being given in the game's files,
and far lesser crimes such as squatting or theft, fraud and a kidnapping that cannot be proven to the suspect,
are all used as justification to commit far more serious murders with the party.
In addition, the fauna is mercilessly slaughtered even though, as usual, they are only defending their territory.

If we apply IRL morality to a game at all, then we should please do so consistently.

For example, there is blackmail by a barmaid,
squirrels who are accused of theft by several parties and who themselves admit to it,
on top of that they also commit the heineous crime of pushing you around the rope bridges in Trynton,
and btw these are not the only scubs in the game.
The Higardi believe a god, and religion is a plague that has been proven to lead to terrible consequences
even for those who do not believe or who believe differently.
Mook, Umpani and Trang are alien invaders who occupy foreign territory.
...

A strict forum isn't the time nor place for nuanced discussion. Although, flinging waste is common on more lax forums. For me, seeking power is evil—my bias, true. Oh, and don't justify it with that great minds and noble souls noise. That's how we got the Stasi, and it's tantamount to background people/NPC theory. I've always seen the Wiz8 party as a band of mercs. Thusly, I find it more interesting to role-play along the law/chaos axis in this game, even if the orgin of the Dandy-esque version boiled down to "we live in a society" v.s. "return to monke." Nevertheless, more should read Poul Andersen—that warmongering cuck. Seems like a reasonable game to role-play an evil Goldpact-esque band of mercs.

Also, that's some amazing bigotry above, I'll just pretend it wasn't intentional. Pfft—always the liberals.

Rattus Rattus: Scumbag. My last party, I whacked him outright. Milano and the Don were Hostile. This party, ignore RR. Talk to the Don and Milano, whack them, then see what RR has to say about it. The result is the same, 3 dead Rattkin.

Crock is a kidnapper, having loyalty to no factions. Whacking him is elementary, as you prevent a kidnapping, and get access to his chest.

The Rapax King is a Kidnapper/Rapist (Immune to Instant Death effects). His son, the Rapax Prince, is a prick (escapes from 2 battles, and dies pathetically from the important one).

Just being a pr!ck isn't enough, as Antone, Kunar, and Glumph, don't directly put you into harms way (as does Rattus Rattus, with the bank robbery).

I suppose that I start with a noble purpose (no Pickpocketing, no Shoplifting, all Friendly NPCs near me have to survive the battle). But then I realize that, both the party and the Dark Savant have both good and evil in them, as alluded to by Marten's Ghost.

In theory, you could murder anybody, with instant death magic (Instant Death, Asphyxiation, Death Wish, Quicksand), and there would be no reaction from any faction. I wonder if this is an exploit, or if this was done on purpose.

This is certainly a concern with the Rapax. For example, you could plow through the Rapax Rift, Courtyard, and Rapax Castle Main Level, and do a certain thing for Al-Sedexus that we won't talk about here. From now on, your faction rating with both the Rapax Common and Rapax Templar are set to Friendly. After slaying your lover, you are now free to leave the Rapax areas (provided you Webbed/Paralyzed/KOed her before she could summon reinforcements).

Now you are official Rapax Templar, and you can visit the Rapax Away Camp without any problems. The Rapax King has his wife, the Rapax Queen, locked away in her cage, and he instructs you to interrogate the Umpani and T'Rang prisoners. Of course, after talking to Drazic and Rodan, you can portal them away to their leaders, but this ruins your faction rating with the Rapax.

Or, you could force your way into the Rapax Away Camp, after having gotten at least 2 artifacts, before visiting the Rapax Castle. Your faction rating with the Rapax Templar starts at Neutral, and you get a friendly warning. However, just push your way in. All Rapax in the immediate area declare war on you, but if you were smart, and high enough level, you would use instant death magic against them. Your faction rating with the Rapax Templar should still be Neutral. Once that battle is over (and a few more minor, unimportant battles remain), you should have cleared most of the Rapax Away Camp, including the Stockade Guard (getting the key to rescue Rodan and Drazic).

Of course, talk to the bratty Rapax Prince, while he teleports away (and his Concubines attack you). This leaves just the Rapax King and his assistant, who isn't special in any way. Kill the assistant with normal instant death magic.

The Rapax King is immune to instant death magic, so must be killed in the normal way, as you would handle any boss (melee combat). However, this will reduce your faction rating with the Rapax Templar, going from Neutral to Hostile. This is why you handle the Rapax King last.

So now your faction rating with both the Rapax Common and Templar are both Hostile. No love lost, as that's just the way it is. Plow through the Rapax Rift, Courtyard, and Castle Main Level, and do the Al-Sedexus quest. Now, your faction ratings with both the Rapax Common and Rapax Templar are permanently set to Friendly, and you can visit Ferro in peace.