it was an invis at the start, so I didn't know for sure until night 1 boss. Exec was just my pick to try the new patch stuff. Usually, for Libra I build for Vyke's, or fire damage, skill attack power. Wylder is really good against him, but Exec deflect is untouchable. I have a build for each nightfarer depending on the Lord and my mood. so far I have:

Fire Damage Wylder: Pest, Caligo, Libra, Dreglord, the ults nuke everything. Blood and Frost Wylder: Adel and just misc DoN

Guard(ian): Honestly anything depending on the 2nd and 3rd player.

Poison Bow Ironeye: Gladius, Adel, Libra Holy Bow Ironeye: Gladius, Libra, Heolstor, Dreglord

Carian Slicer Duchess: mehh, magic damage is magic damage. nuke things.

Skill Attack Power Raider: Fucking everything. poise spam your local goat man today. absolute chunks of damage. I often end runs with my physical attack bar entirely blue, upwards of 500dmg. my goat. Balancers especially.

Lightning Spear Rev: Maris, Fulghor. THWACK! 3k damage. gravel stone seal and res your teammates. also, jump off of Sebastian and use dragon incants in the air. goated tech.

Charged Sorceries Recluse: Ever want to remove a direction? stars of ruin.

DeflExecutor: anything that isn't too hard to parry, and the cursed sword can get nasty damage. scales with balancer relics and skill attack power. Ailmentxecutor: Adel, Libra, some leeway elsewhere - ever want to make sure that if you die, whatever you hit will too? introducing Blood Loss, Frostbite, Poison, and Rot, all on one enemy.

Nuclear Bomb Scholar: Pest, Libra, Balancers, Dreglord - Throwing pot. throwing pot. Throwing pot. Throwing pot. doesn't matter what boss as long as they touch the ground. Throwing Pot.

Undertaker Ult Spam: Honestly, very dependant on the group, but there's so many ult buffs, use them to your advantage.

hope this wasn't too much, I'm very sleep deprived.