Iron heart surge

Instantaneous effects can’t be removed by iron heart surge. However, any effect with a duration of 1 or more rounds, including permanent-duration spells or effects, may be removed by iron heart surge, nor does iron heart surge restore damage or ability drain. Iron heart surge doesn’t replace lost levels (though it would remove any negative levels resulting from a single spell or effect). It would neutralize a single poison coursing through your system, or a single disease that afflicted you.

- How IHS works according to Sage

The Iron Heart Surge is perhaps the zenith of Weeaboo Fightan Magic ignoring common sense for the sake of being "cool." It is more-or-less exclusive to the Warblade class.

Iron Heart Surge can do this because of some of the most spectacularly bad wording prior to the inception of the Pyrovore. It was intended to copy the age-old anime move where the user yells and flexes their ways out of a bind. The problem is that IHS is a maneuver, something you need to be able to take a Move Action for. And if you're, say, tied up, paralyzed or stuck in a web you cannot move and as such cannot use IHS. But because of its wording it can do a lot more than intended...

The IHS essentially lets you pick any ongoing effect or condition affecting you and end the source of this effect. Not the effect itself: its source. Instantaneous things like fireballs and one-time damage cannot be targeted, but as long as it lasts longer than one turn (including permanent effects) and does not stop you from moving you can end the source of something bad happening to you. This means that if you're caught in a blizzard that deals cold damage over time or in a desert which hurts you to dehydrate, all you need to do is a good old Iron Heart Surge and the blizzard vanishes and the desert no longer deals heat damage. It can also be used to remove poison or disease ("Yes, Timmy. It's your fault that you're dying of cancer at age seven. You should have dipped Warblade") but negating Antimagic Fields or Cloudkill spells is nothing short of bizarre.

It can even alter effects such as being blinded by the the sun: look into it, use IHS and BAM! Sun's gone. Fell into the ocean and started to drown? IHS and BAM! Ocean's gone. Make sure to bring something that mitigates falling if you do this. Go to the Elemental Plane of Fire and start taking fire damage? IHS and BAM! Fire's out.

Some argue that you can also use this to kill monsters with: get swallowed whole by a Purple Worm, get dealt ongoing acid damage, use IHS and BAM! Purple Worm's gone (though a smart GM would argue that only the acid disappears). Force-feed yourself to the Tarrasque and FLEX YOUR WAY INTO LEGEND.

/tg/ talks about IHS and how to abuse it

Abbreviation 'IHS', is incidentally also a Christogram - implying that you're FLEXING WITH THE POWER OF JESUS CHRIST and not your own.