The only other protection card I could find that removes threat from any scheme and not just the main scheme is True Grit, which might remove the same amount of threat on average but doesn't give any defensive advantage. That makes this a noteworthy card for Protection solo play, which struggles with threat removal, especially on side schemes. Not Today! is comparable to several other protection staples: Never Back Down, Desperate Defense, and Jump Flip. Each has their own advantages and depends on your hero and what scenario you're facing, but Not Today! has its own niche against side schemes. I'm not thrilled about relying on this as your threat removal, because you'll often want to remove side schemes on your own turn instead of waiting for the villain phase (if it has an acceleration icon, for example). A play pattern you can do that's good against a crisis side scheme, for example, is to thwart it down to 2 on your turn, then finish it off with Not Today! in the villain phase before the extra encounter card gets dealt.

I'm still not a big advocate of solo Protection decks built around defending a lot, but if that's your jam, you'll probably want this card!

Great combo card to put in Bait and Switch decks. Now you can thwart both the main scheme and a side scheme or just go for 6 threat removal on the main scheme! Combine it with three Hard to Ignore, and threat removal is getting nuts in protection :)

With this card, we now have 4 Protection cards that do ALMOST the same thing with finicky differences, the other three being True Grit, Jump Flip and Hard to Ignore.

True Grit is probably the worse of the quartet. For 2 ER, you remove at most 2 threat (well, 3 if you're playing Phoenix, Spectrum in Photon form, or max level Ironheart), which is a mediocre ratio. It also hasn't any particular synergies with other Protection cards, since it's a THWART Event, not a DEFENSE. The silver lining is that you're not limited to removing threat from the main scheme, but it's not saving the card from utter mediocrity.

Jump Flip and Hard to Ignore are arguably on par with each other, each suited to slightly different scenarios but also capable of synergizing well with each other. Jump Flip is more flexible as it's not dependent on defending using other means than itself, but it has an annoying energy resource requirement (which nevertheless works well with Nerves of Steel), while Hard to Ignore has a better threat removal / ER ratio in the long run but has a no-damage requirement that makes it better suited for high-defense heroes who like to defend a lot, in conjunction with Armored Vest, Expert Defense, Desperate Defense, Never Back Down, or Riposte. However, the big drawback here is that both only remove threat from the MAIN scheme, which sometimes can be very limiting.

Personally, I think that Not Today! is the best of the four. It's similar to Hard to Ignore in terms of what it does and how (and in fact it benefits from the same card synergies), but it's not limited to removing threat from the main scheme, intrinsically helps you reach the no-damage requirement, and it's a DEFENSE Event which benefits from cards such as Flow Like Water, Defensive Energy and Nerves of Steel. It synergizes well with its three brothers, but I would never include all four in the same deck (certainly not True Grit, and I would choose Jump Flip over Hard to Ignore only if my deck reliably provides a lot of energy resources and/or my hero isn't very good at avoiding damage entirely). Combine with Bait and Switch if you're playing Solo against heavy-scheming villains, or in multiplayer to be hailed as the definitive support hero (especially if there are no heroes with the Justice aspects).