It really hurts me to do this but...
We do use the post April 17, 2001 version of canni.
http://www.tski.co.jp/baldio/patch/20010417a.html
Cannibalize IV now exists. This spell is now available in Velious.
Cannibalize II and III have had their effects improved. They now return more mana to the caster than they did before.
Cannibalize III
-78 HP / + 36 to 38 Mana
There is no details for Canni II though.
http://web.archive.org/web/200104260.../allspells.htm
The other thing to note for Avatar is: +100 Strength, Dexterity, Agility, and Attack Avatar requires an Emerald to cast. It will overwrite our 57 Strength buff, and has a recast delay of 3 minutes.
On topic though it does not list any mana drain on Torpor: Torpor will regenerate 1200 HP over 4 ticks, however while in effect it will snare you, and reduce your attack speed (note: Some Shaman have reported Torpor doing 1540 over 5 ticks).