From WoWWiki
Improved Spirit Tap is a talent in the Shadow tree, you will need to spend 5 points in Shadow to max it. It increases total spirit and mana regeneration on a Mind Blast/Shadow Word: Death critical strike.
Rank table
| Rank | Spirit | Mana regen
|
| 1 | + 5% | 17%
|
| 2 | + 10% | 33%
|
Patch changes
- Patch 3.2.2 (2009-09-22): Mind Flay periodic critical strikes now have a 50% chance to trigger this talent.
- Patch 3.1.0 (2009-04-14): Now grants 17/33% of mana regeneration while casting.
- Patch 3.0.2 (2008-10-14): Added.