How would you suggest subduing (not accidentally killing) a super villain with fire powers?
So, the villain has flame based powers, or you want your characters to subdue them without accidentally cooking them?
If your characters are going up against someone who has fire-based powers, then they’re going to need to understand the limits of those powers. This is something I feel we’ve said many times before. The entire idea of taking down a super villain (or superhero, for that matter) needs to start with getting accurate intelligence on what they can do, and (more importantly) what they cannot. In many cases, that means they’d need to find ways to test that character’s limits, though if this is a hero or villain who’s been active for decades (or longer), that information may already be out there.
Also, the overall power of a character is vitally important. A character with minor pyrokinetic abilities could be pretty easily subdued with mundane methods. A character who is a living avatar of flame, and no recognizable physiology, would require a significantly more specialized approach. What options are available is entirely dependent on your world building. So, at that point, “best,” is very flexible.
Now, let’s flip this, because dangling modifiers are awkward. If your character has flame based superpowers and they’re going after a villain, the answer is probably to incorporate more options into their toolset.
This might not be immediately apparent, but having the ability to set things on fire with your mind isn’t an incredibly useful ability. Sure, it makes caramelizing creme brulee a snap, but outside of bar tricks and setting people on fire, there’s not a lot of utility that doesn’t end in death, suffering, or BBQ. This creates the odd situation where you have a superhero who really needs to supplement their superpowers with abilities that won’t result in catastrophic property damage.
For your superhero that means they’re going to need to train in mundane skills. They may be able to subdue a foe using a tazer or tactical baton. They may need to know when to point someone else at their target, or when to walk in and draw attention while someone else subdues their errant supervillain.
Social skills are another legitimate option. A character may be very persuasive, even ignoring their abilities, so it’s not entirely impossible that your superhero’s plan is to talk the villain into surrendering.
Talking a character down operates off the same process as above. It requires your characters learn about their opponent, discover what’s causing them to act, understand the reasoning behind it, and formulate arguments to convince them to take another path. Even then, your characters are probably going to need some good followup points. Dialog like this is as much of a fight as combat, it’s just the structure and outcomes are different.
Even if it doesn’t work out, trying to talk the villain down is a very “superhero” behavior. It is the best recourse before things get messy, and people get hurt. This is especially true for a character where their innate powers are inherently destructive.