Questions about Benhart of Jugo achievement

[Nikko]

Hi everyone, I have some questions about the Benhart of Jugo achievement:
I summoned him in the Prowling Magus and the Looking Glass Knight boss fights, and Benhart survived both. However, today, while I was doing the Giant Lord, Benhart died just a second before I could finish the boss.
My questions are:

1) Can I use a Bonfire Ascetic to summon him again? Like, if I wanna kill again the Prowling Magus (easy fight imho), will I be able to summon him, and will this victory count for his quest?
2) If I can't, will I be able to summon him for Nashandra fight or he's dead forever?
3) I read about a bug about his questline but did not understand what it is about, can you explain me?

Thank you kindly

[HoneyDrake]

you can bonfire ascetics and fight with hi again

[The Blue]

from my understanding of this quest. there are 4 boss fights you can summon him to. he has to survive 3 of them. if on the next fight he dies before it's finished. exit the game and try again. this video covers everything you need.
http://www.youtube.com/watch?v=s2mN9seebAA

[Korburss]

You can use Ascetic's to redo the boss and it will count.
You can resummon him as many times as you have boss to summon to.
The bug is: If you fight the Throne Watch and Defender with out the Giant's soul, Nashandra doesn't spawn and she will not count when you do. However if you summon him and fight Watcher and Defender, then Nashandra it counts and it will count even if he dies on Nashandra and you throw the fight and redo only her part of the fight.

[Nikko]

Thank you very much guys, one last question, can you tell if the Prowling Magus fight is as easy as the ng fight with the ascetic?

[Korburss]

Prowling Magus isn't really that much harder even into NG++. Just roll to avoid lightning, blast down Priest/Mage if you have range or circle around if melee, and hide behind the pews as needed.