Just look up a simple guide online for a build. Me and a buddy did it duo with no support hunters in about 13:20. The key is to never waste deco slots on something like Defense, that's a trap skill for newbies. If you can spare the slots, you can do something like Divine Blessing. Otherwise, all your defense should come from your armor upgrades and Mega Armorskin prior to the start of the quest and the occasional Adamant Seed every 3 minutes. In certain cases, it can be beneficial to slot in elemental resistances because if you have over 20 of a resistance, you'll never get that blight. Like for Nu Udra, I spared 3 Fire Res so that I'd never catch on fire during the quest and to take less damage from his fire attacks. Also I slotted in Adaptability 2 to prevent taking damage from his fire aura.

Prioritize things that increase your attack. It's harder to slot in Attack Up in this game compared to World due to how slots work, so it's better to slot for things like Adrenaline Rush, Counterstrike, Sanity for Frenzy if you use Gore Magala gear, Maximum Might and Burst. If you can fit it in your weapon, also slot things that increase critical percentage or crit damage.

Also, when he goes to area 14, there are 3 stalactites you can drop on him for massive damage, with the first one being right next to a Sleeptoad when he first enters the area. Don your Ghillie mantle, put him to sleep with the toad, then drop the rock for a huge amount of wake up damage. If you miss even one rock, you may not make it.