Shadow priest Glyphs

[CAYRA]

Do these two glyphs stack with the talent "twisted Faith"?
Glyph of Shadow Word: Pain (Use: Increases the damage done by your Mind Flay spell by 10% when your target is afflicted with Shadow Word: Pain)
And
Glyph of Shadow(Use: While in Shadowform, your spell critical strikes increase your spell power by 10% of your Spirit for 10 sec)
Thanks a lot!

[Nezoia]

Yes, but not nessary directly.

[Kelesti]

Twisted Faith, Glyph of Shadows, and Improved Spirit Tap all synergise well together. Not really sure what the point of referencing Glyph of Shadow Word: Pain there, though.

[Uhuuu]

Because it has the same effect as twisted faith I'd guess :P