So it is "will to power" and not "will to life". To me the best way to avoid putting these directly at odds is to look at what "power" actually means from a perspective like post-Marxist-Feminism of Starhawk or some other position that deeply undercuts the power of both kings and martyrs.
This is a vast oversimplification, stripped of all the feminism. (It is a little punchy, because Nietsche and Starhawk both seem to really like bad jokes.)
The power to kill is a dumb power. Once you use it, the person you used it on is not going to do much for you. It is only power until you use it. Ultimately what you are really using is not the power of death, but the fear of death. This is the cocaine of power -- it makes you very effective, but then it is gone, and you immediately need more. It goes away not just when you kill people, but a little bit every time you use it as leverage. (So you never know exactly when you are running out.) It is a very contingent power. It depends on the target wanting life, which depends on the quality of their life, which you are actively degrading by threatening to kill them. At some point, they can face death to be rid of you.
This is most tractable if they have already given up their life. But that is what martyr-religions do -- you give up your life to God, so that someone else cannot take it away from you. This is the heroin of power, it makes everything alright. But the downside of heroin is captured in the joke behind the name of the band 'Sublime', it feels heavenly, which is sublime the adjective. Sublime the verb means for something solid to basically disappear (untraceably into gas), which is what your life does ("All this love that I've found makes it hard to keep my soul on the ground" -- too hard. He did not succeed for very long.)... Nietsche's argument was that this was what is happening historically to the vitality of Europe, under the force of equality-based moralities, and what happens to the real soul of any good Christian, it evaporates, unnoticed.
OK, well cocaine and heroin are stupid. They convey certain abilities and experiences to you, but they are likely to change who you are. Their corresponding versions of power are equally stupid, in the long run, in the ways that they overpower and degrade their wielder. If your own power overpowers you, who then has the power? -- The power has itself, and the holder loses. This explains why these forms of power are so persistent. Not that they are 'more real', but that they are addictive.
It would be better if your menu of power looked less like the inside of Hunter S. Thompson's trunk, and more like the top of Martha Stewart's table. To remain vital, an individual, and a culture needs to develop a reflexive refusal to buy into the strong stuff and find subtler, more sustaining joys.
So don't kill, in general. Not because someone said so, and definitely not because "everyone deserves to live", but because it is not sustainable. You don't want to be the master whose head got cut off by his slaves, or share even a part of his mindset -- he lost. But don't check out of material reality into some better place, either, or you will just evaporate. Instead, figure out what parts of power you can enjoy exceptionally well, that are unlikely to degrade your ability to continue to enjoy them for the long haul.