I don't really even understand the proposition of rules being used to resolve problems like this. I haven't had the time to read the entire thread EW (although I did read the first page) because of other demands but when it comes to tactics there is an extremely easy solution, counter-tactics.
You just do (as a DM) what anyone with any experience would do in a similar situation in real life.
1. A person or team tries a tactic or trick to employ against an enemy.
2. Assuming the party being attacked survives the initial assault, or any part of that party survives, or an observer survives to report upon it, then the party being attacked (if it has any sense) will immediately try to place thermoses in a position which allows either defense against the tactic or in one in which they can take appropriate countermeasures.
3. An attacking teams tires the same tactic or maneuver every time and soon enough word gets out and enemies adapt. Nullifying, mitigating, or countering the initial tactic. If they (the enemy) have any sense at all then they will also develop their own set of tactics to exploit the weaknesses of the other party or those of their own enemies.
The very idea that rules are needed to resolve such situations assumes that enemies are completely static in their responses and adaptations (even animals adapt their tactics when it becomes obvious normal attack methods or defense methods are inadequate, at the very least they flee an encounter, which lessens the effectiveness of most attacks), that the same tactic works all of the time or most of the time, that situational variables are likewise static, and that enemies will not counter or mitigate tactics and develop tactics of their own. But that's just not the way any combat situation or encounter ever goes unless the entitle tactics are completely and totally successful (that is they are always lethally effective in every situation the very first time they are employed). And that so rarely happens as to be the real exception to the rules of warfare and combat not the standard.
The whole idea of an enemy (or by extension the DM) needing rules to resolve what are essentially combat tactics is kinda silly to me. All the DM ever has to do is be as clever or more clever than the players, and not even that all of the time, just some of the time.
You don't have to "game-limit everything" (if a guy were slinging flaming oil at you in a street battle would you then cry out, "hey, that's against the rules, you've already done that once today - no fair!", or by observation of the earlier encounter would you not be ready with a counter-measure?) when perfectly acceptable tactical solutions are easily developed.
In a modern, real world sense, if a guy were throwing flaming oil at me I'd shoot the container and spill it on him. Let him and his friends burn awhile. I'd ignite or destroy his ammunition supply, I'd seek cover, I've employ sabotage, etc, etc. In a game sense I'd employ magic or flaming arrows, or wet leather-covered shields, or whatever was appropriate to have the same effect. For almost every attack there is an equally effective counter-measure or defense (assuming the appreciate supplies are available and if not then sooner or later enemies learn to make it so). It is a rule of nature. (Of course you can't nullify an effective ambush but what you can do is set up your own effective ambushes as a counter-measure.)
I admit I just don't understand the tendency in role play games to "rulerize" (as if that is a real solution, instead of what it really is, an avoidance of convenience of the issue, tactic, problem, or obstacle) everything when far simpler and more effective and tactically ingenious and practical and interesting (role play) solutions are readily available in almost every situation.
It is a tendency, I think, in modern RP gaming to "not think of a real solution" and instead reorganize the initial assumptions so as to (a)void real creativity and innovation. The game is trying too hard to be a game in such circumstances and limiting human capability.
I'd never tell my players they couldn't pursue any tactic or exploit they so desired, or could devise. Quite the opposite, I invite innovative cunning. But over time I would counter those tactics with tactics of my own forcing them to develop ever fresher and more clever tactics, while I do likewise.
The point is not to suppress innovation, it is to encourage, exploit, and enhance it. You want your players to become ever and always better and smarter at what they do. That encourages the DM to do the same. It's not a contest to see who can be the most static and inflexible, but who can be the most fluid, dynamic, and ingenious.
I hope the game moves ever farther away from artificially and rule contrived tactical exercises and more and more towards organic and fluid tactical genius, when it comes to combat. Hell when it comes to anything for that matter. That keeps the game from being a mere exercise in lawyering. Rules should be the last thing anyone should turn to in exploiting innovation and creativity and cunning. (Rules are by very definition often the opposite of innovation.) Cleverness isn't honed and exercised by "rulership" and artificial arbitration, it is developed and nurtured by brilliance and counter-brilliance. Crafty completion breeds a better man, not regulation (though sometimes necessary regulation may also be an obstacle that encourages further cleverness).
Well I hope I didn't just repeat what someone else has said (maybe better), but as I said, I'm typing and scan reading on my free time, which is limited lately. I hope I didn't make too may typos either.
See ya later.