According to Dec 1st patch notes,
- Haynar: Mana drain spells will no longer drain bard mana.
However, enchanters are still able to drain my bard's mana. This was observed from the bard's perspective as losing mana. The enchanter said he was using Theft of Thought, Torment of Argli, and Lagarn's Lamentation to drain mana.
Haynar's fix appears to have not made it in to the Dec 1st patch.