Composable NOT Guider (Liu et al. 2022)

A normal negative prompt in ComfyUI is not a subtraction. It's the empty prompt with stuff in it, and CFG extrapolates away from it. The two are related but not the same, which is why negatives behave oddly when you write them too strongly or stack several concepts in one box.

Composable NOT (Liu, Li, Du, Torralba & Tenenbaum, ECCV 2022) is the literal version, from the composable-diffusion line of work: u + w(c - n), where u is the true empty prompt, c is your positive and n is the negative. Your positive is measured from the null and your negative is subtracted from it as a direction to leave. Clean, explicit, and it explains why the same negative text "works" differently here than it does in the KSampler's box.

Why this is a guider, not a model patch

Everything else in this pack patches a MODEL and hands it to your existing sampler. This one produces a GUIDER, which means it goes into SamplerCustomAdvanced's guider input, not into a KSampler.

That's the first thing that trips people up. The second is that it needs three conditioning inputs:

• positive - your prompt's conditioning.
• negative - the thing you want to move away from.
• null - the empty prompt. The node's tooltip is blunt about it: "the true unconditional."

You need to wire a genuinely empty CLIP Text Encode (blank text) into null. If you wire your negative prompt there - or reuse the same conditioning object - you're no longer doing composable negation, you're doing something else with three copies of the same vector, and the results will be nondescript in a way that's hard to debug.

• cfg (default 7) - this is the guider's scale. There's no separate scale input: the guider owns it because SamplerCustomAdvanced's guider path doesn't take a cfg widget the way KSampler does.
• space - auto uses the method's published space.

One GUIDER output, into SamplerCustomAdvanced.

The cost

Three predictions per step: positive, negative, null. Plain CFG gets two (and one if you're at cfg 1 with the optimization on). So this is roughly a 50% step-cost increase over classic CFG, on top of losing the CFG-1 shortcut. It's a tool for a specific job, not a default you leave in.

Install

# ComfyUI Manager: search "CFG Megapack" -> Install -> restart
# or:
comfy node install comfy-cfg-megapack
# or by hand:
cd ComfyUI/custom_nodes && git clone https://github.com/AbstractEyes/comfy-cfg-megapack

No dependencies, nothing to download, ComfyUI ≥ 0.38.

Related nodes in the same menu

The pack ships a general-purpose CFG Guider: Positive, Negative and Null which exposes several three-way rules - perp_neg (subtract only the part of the negative perpendicular to your positive, so a negative can't cancel what you asked for), separate_negative (the composable-negation form implemented here), and negative_as_null (plain CFG, for reference, and stated to be bit-identical to ComfyUI's own CFGGuider). If you want to compare this node against something, use negative_as_null - it's the control.

The perpendicular variant is the one to reach for when your negatives are fighting your positives, which is the usual cause of "my negative prompt is eating my subject". Composable NOT, by contrast, is for when you want an unambiguous subtraction and don't mind it being strong.

One more: the model's other CFG Megapack stages still apply to this guider. If you have a schedule or a correction on the model wire, it's still in play - which is either exactly what you wanted or a surprise, depending on whether you remembered.

Two things to know before you spend an hour on it

The pack forces three passes, so the negative actually runs - unlike at CFG 1, where a guidance-distilled 2026 model has no unconditional pass at all and the negative box is inert. If you're on Z-Image Turbo or a Klein distilled build and you want working negatives, this is a legitimate route: the guider constructs the passes explicitly. Just be aware you're paying for two extra forward passes per step, which is most of the reason those models are fast.

A wrong null gives you nonsense, not an error. Blank CLIP Text Encode into null, always. And if you want to check what the model is actually running, drop CFG Plan Readout on the model wire - it prints the full plan, stage by stage, in the order it executes.