I'm not exactly sure what happened here, so it may or may not be a bug.

Vorondel yells 'Die, Dahrozirn, you sorcerous dog!'
Dahrozirn utters the words, 'eugfjsh afoai'.
Vorondel doubles over in pain and coughs up blood.
Dahrozirn's disruption EVISCERATES Vorondel!
Vorondel yells 'Die, Aiekooso, you sorcerous dog!'
You create a geyser aimed at Vorondel!
A sifaka lemur squeals somewhere nearby.

Your geyser === OBLITERATES === a sifaka lemur!
Your geyser decimates Vorondel!
The gods protect Amiwiel.
The gods protect Gonnosuke.
The gods protect Jallas.
A sifaka lemur is covered with bleeding wounds.

<1026/1092hp 1186/1232m 836mv> PM> 22700tnl c 'geyser' vor

Vorondel's pound injures Gulthruck.
Gulthruck's infernal power MUTILATES Vorondel!
A sifaka lemur's bite grazes you.
A sifaka lemur dodges your magic.
A sifaka lemur is covered with bleeding wounds.

<1021/1092hp 1186/1232m 836mv> PM> 22700tnl
A sifaka lemur leaves north.
A sifaka lemur has fled!

<1021/1092hp 1186/1232m 836mv> PM> 22700tnl
Gulthruck leaves south.
You follow Gulthruck south.
Redhorn Gate

I never engaged Vorondel and as far as I could tell the lemur didn't distract either. Why did I engage the lemur first when the spell was directed at Vorondel?

<1020/1092hp 1173/1232m 769mv> 22700tnl c 'geyser' vor

Jallas utters the words, 'cancellation'.
Vorondel yells 'Die, Aiekooso, you sorcerous dog!'
You create a geyser aimed at Vorondel!
Your geyser decimates Vorondel!
The gods protect Amiwiel.
The gods protect Gonnosuke.
The gods protect Jallas.
Vorondel's pound wounds Nancheun.
Nancheun's cleave injures Vorondel.
Vorondel parries your magic.
Vorondel parries your magic.
Vorondel has some small but disgusting cuts.

<1020/1092hp 1140/1232m 769mv> 22700tnl c 'dispel magic'
c 'stoneshatter'

Gulthruck's infernal power maims Vorondel!
Nancheun's cleave injures Vorondel.
Nancheun's pierce hits Vorondel.
Vorondel parries your magic.
Your magic hits Vorondel.
Vorondel is covered with bleeding wounds.

<1020/1092hp 1140/1232m 769mv> 22700tnl The magic of the giant strength spell unravels.
The magic of the metabolic quickening spell is unaffected.
The magic of the aura spell is unaffected.
The magic of the ocular enhancement spell is unaffected.
The magic of the ocular enhancement spell is unaffected.
The magic of the detect magic spell unravels.
The magic of the fly spell is unaffected.
The magic of the barrier spell is unaffected.
The magic of the shield spell is unaffected.
The magic of the malleability spell is unaffected.
Vorondel is covered with bleeding wounds.

<1020/1092hp 1125/1232m 769mv> 22700tnl
Nancheun leaves north.
Nancheun has fled!
Jallas looks at Vorondel.
Vorondel is covered with bleeding wounds.

<1020/1092hp 1125/1232m 769mv> 22700tnl
Jallas looks at Vorondel.
Vorondel is covered with bleeding wounds.

<1020/1092hp 1125/1232m 769mv> 22700tnl c 'geyser'

Vorondel utters the words, 'hzrzsafh'.
Vorondel vanishes!

This happened right after. I had him engaged in combat and he teleported out of combat.