Removal of low level branding spells.

[khalil]

but also provide a large boost that scales up with the power of your weapon, making them more relevant late game than early game, despite the low cost and low level. That's very different from magic dart, obviously.

But that doesn't apply to Lethal Infusion, which becomes less useful late game as undead, demons, and constructs become more common, to the point where it is completely useless in Hell, Pan, Crypt and Tomb. That's 10 runes where the draining brand is so much dead weight. (It's also fairly useless in Abyss, but there are a few monsters it works on there.)
EDIT:
Actually, just remembered Pan has demonspawn now. So that's 5 runes(Tomb and Hell) where it's useless and 6 runes(Abyss and Pan) where it's almost useless.

[and into]

but also provide a large boost that scales up with the power of your weapon, making them more relevant late game than early game, despite the low cost and low level. That's very different from magic dart, obviously.

But that doesn't apply to Lethal Infusion, which becomes less useful late game as undead, demons, and constructs become more common, to the point where it is completely useless in Hell, Pan, Crypt and Tomb. That's 10 runes where the draining brand is so much dead weight. (It's also fairly useless in Abyss, but there are a few monsters it works on there.)
EDIT:
Actually, just remembered Pan has demonspawn now. So that's 5 runes(Tomb and Hell) where it's useless and 6 runes(Abyss and Pan) where it's almost useless.

If you needed to clear Crypt or get 10 runes to win the game, that would be relevant. Since they aren't, it is not.

Yes, there are a number of things in Zot that draining doesn't work on, and a few dangerous enemies in depths/Vault:5 that draining won't help against. This doesn't diminish the point at all, because "level two spell that becomes stronger in late game, oh except arguably* Zot and V:5" is problematic in exactly the same way as is a level two spell that becomes stronger in late game, including Zot and V:5.

*I say arguably, because draconian packs and orb guardians are the most dangerous things in Zot, and they are susceptible to draining. Plus, most of the stuff draining doesn't work against is undead—and thus has other pronounced and exploitable weaknesses anyway.

[khalil]

@and into
Point as far as those branches being optional goes. However, I disagree with you on Draconians and Orb guardians being the most dangerous things in Zot. While draconians are most definitely the most common things, I'd probably give the prize for most dangerous to either Ancient Liches(3d30(average 45, rounded down) damage at the best, 9d20(average 90) at the worst), Electric Golems (3d20(30) isn't that bad, but multizaps can have that hit you several times), Curse Toes(Torment), Orbs of Fire(3d40(60) damage and bad mutations), or worst of all, DEATH COBS(This is a joke, much like Death Cobs themselves). Orb Guardians are fairly mundane, all things considered.

[and into]

Yes, and despite those terrifying stats, draconians and orb guardians kill more players (IIRC) than orbs of fire.* Certainly they kill more than electric golems and curse toes. This is because they spawn in packs, are much more common, can be berserked by moths of wrath, and also tend to be underestimated. (In addition draconian packs can do about a million different combinations of things, depending on composition, that you have to keep track of.) Those factors matter just as much—indeed, more so—than the maximum damage that a single example of an enemy can do.

An analogy: Orbs of Fire and ancient liches are dangerous in the way a particularly tough unique is dangerous in the mid- or early game. Draconians and orb guardians are dangerous in the way harpy packs in Shoals when you are level 15, or nasty orc packs in early game are dangerous. This second type of dangerousness is far more lethal in far more cases.

*Okay, not actually true, my apologies. OoF have most kills. But orb guardians and draconians are second and third, and thus ahead of electric golems, curse toes, ancient liches, etc., despite those enemies having better resists and higher max damage capacity and scary spells, etc., so the larger point stands.

[Siegurt]

What if branding spells were capped at the (base damage size) weapons they could enchant by spell power?

Something like:

Brand only works if (BaseDamageOfWeapon) <= Spellpower/5.

This limits the level 2 spells (with their spellpower 50 cap) to 10 base damage weapons (and then only once you invest to max the spellpower, which while still not a large deal, is no longer the 'extremely trivial' amount that it takes to get them barely castable)

[khalil]

I'm not really sure how to check the death statistics, but I will say that I was considering including Moths of Wrath on my list.

[TheDefiniteArticle]

Orbs of fire have the most kills in Zot. Orb guardians are second, and draconians are third. "Orbs of fire resist it" is a bad metric by which to measure the power level of anything, though, because even if the numbers were different, the monsters that are vulnerable to any specific thing are still numerous throughout Zot (see also parrow and pcloud).