Takin' Down the Beast

Not sure if it's changed all together or because my covenant is Venthyr but the only thing I needed to attack him was [item=176397], didn't need to repair the Ballista.

Takin' Down the Beast is a quest given by [npc=165327] to kill [npc=165290].
[npc=165290] is located in the Revendreth The Banewood zone.
Rare is flying near the cliff South of Wanecrypt Hill flight point.
It is immune to damage until you shoot it with [npc=165324].
First you have to repair the Ballista, bring 2 [item=176396] to [npc=165325].
You can find the tools inside the north building of Dredhollow
and in the cart outside of the building.
To use [npc=165324] you have to bring [item=176397] to [npc=165327].
[item=176397] is inside the castle west of [npc=165324] near the wall.
Has a chance to drop [item=180461].

Rare is a part of Adventurer of Revendreth achievement.

/way 45.83 79.34 Harika the Horrid
/way 43.23 77.62 Dredhaven Bolt
/way 40.77 72.70 Dredhollow Tools
/way 41.18 74.67 Dredhollow Tools
/way 46.30 77.86 Wingsmash

Harika the Horrid video: https://youtu.be/zxA7zfXg8P8
Dredhollow Tools: https://youtu.be/AyIEodWam80

Ivrim is right. 1x Dredhollow Bolt is enough to start the fight.