Blast Attack is a Skill in Monster Hunter World (MHW).
When you deal blast status, you deal raw damage, and also build up the blastblight gauge. If you were hitting with poison, you would deal regular damage and also build the poison gauge. When maxed, you will inflict the 'blast' status. In MHW, Blast is interesting because it deals a ton of damage all at once to an unbroken part and the surrounding hitboxes. Blast, since it originates at an unbroken part, is excellent for breaking hard-to-reach places. It seems that the part chosen is random. Since the explosion is somewhat large, it can also hit other parts at the same time, as well.
This means that the blast attack skill /will not/ increase the damage you do in the short term. Each momentary hit does not benefit from the skill. But the build-up of that gauge gets drastically sped up, and when it triggers, that blast damage will get a bonus from the +10 bonus as well. What this translates to is more frequent explosions centered in unbroken body parts, and higher damage from those explosions when they happen.
This is a bit of a departure from my previous experiences with blast. In the old days, it used to deal a large amount of damage to every unbroken part. That meant that its use tapered down over the course of a fight, but that you could effectively guarantee getting all your breaks. In this new system, if all parts are broken, it seems blast afflicts the target center mass and hits whatever hitboxes it hits, which gives it great staying power in longer fights, too.
Breaks are incredibly important, as I'm sure you know (but I just want to be thorough) because every break gives you an additional reward off the carve table at the end of the quest, even if they don't give you a physical drop to pick up.
If you get a bow with blast coating and wyvernshot a monster from head to tail or vice versa a couple times, you can usually break everything they've got pretty quickly. If all you're after is parts, I've seen it done that you open with blast coating bows, break all the parts, then farcast back to base and get your real weapons.
That said, if you're still using the bow, wyvernshot /does/ benefit from your current coating, and the extra damage from it /does/ build up the blast gauge faster. I can usually inflict (in low rank) a blastblight every wyvernshot or two.
And if you want to make money, blast coating on a bow, wyvernshot, and the bandit's mantle, on a low rank mission. The absolutely terrifying amount of special breaks you can get with that sort of setup is mind-boggling. I made 15000 zenny in one engagement with a great jagras, lol. The bandit's mantle is sort of a status in itself. You don't have to get real breaks, but all the damage you do gets put toward a special 'bandit gauge' and filling that cause a trade-in item to drop from the monster.
Additionally from Alexandeyr:
I've done some science, and it appears that in MH World that blast affects parts that are breakable, but not parts that are severable. The methodology was to use blast dual swords and perform the following tests on the great girros with the zorah magdaros dual swords, which deal cutting damage and blast status.
1.) attack only the front end of the monster. As expected, this shattered his face and hands rather quickly, but it did not on its own sever his tail.
2.) attack only the tail. This did not break his front parts. The tail was taken at a normal rate. The blast did not seem to accelerate the taking of the tail in any noticeable amount.
3.) attack the front end of the great girros for approximately half the fight, then move to exclusively attacking the tail. Results for the front parts were as expected, but the tail took just as long to sever as it had when exclusively attacking the tail to begin with.
4.) attack only the tail until the tail is severed, then move to the other parts. In this scenario, the tail took the usual time to sever, but the other parts took only a handful of attacks to break, in many cases breaking in as little as one press of the circle button in demon mode (a spinning advancing slash that deals multiple light hits).
Using the results from these tests, it appears that the blast damage does not affect the threshold for severance as it is believed to have done in past games, but that it /does/ affect all breakable parts without regard to how far they are from the point of impact of the attacks, though it seems to require an additional physical hit to actually reduce the parts to the broken state.
The following are the conclusions that I'm going to tentatively draw:
1.) blast damage on its own cannot sever a tail
2.) blast damage on its own is unable or unlikely to actually break breakable parts of the monster.
3.) blast damage does not add to the cutting threshold to sever a tail.
4.) blast damage /does/ affect all breakable parts, reducing them to a very low amount of health without actually breaking them.
This would seem to suggest that if you have a cutting weapon and the blast status that your best bet for taking a severable tail and also breaking all parts of the monster is to focus your attacks on the tail, and then, once you have taken it, move on to the other parts, which should have been weakened considerably by the blast status damage from your earlier efforts, and which can be broken easily with either cut or blunt damage. --working the opposite way, from front to tail, makes it more difficult to sever the tail because you now have to reduce the tail's severance gauge to zero while racing the monster's actual health bar, which will have been weakened considerably from your efforts to remove its breakables.
Blast Attack Effect
Blast Attack is increased in level based on the amount of Equipment with this skill the hunter is using. Each level works as follows:
- Level 1: Blast buildup +5% Bonus: +10
- Level 2: Blast buildup +10% Bonus: +10
- Level 3: Blast buildup +20% Bonus: +10
Equipment that grants Blast Attack
You can increase the level of Blast Attack by equipping the following items.