These synergies combine in dizzying ways: Horrid Shadowspinner attacks to return Sneaky Snackers from the graveyard
Other than being a way to enable the rest of your deck, shes also removal for creatures, and a win condition if you get to ultimate her
You can stick with Edgar Markov and build an aggressive Vampire deck by adding more lords, Shared Animosity, and other aggressive tribal-matters cards, or you can go with Licia, Sanguine Tribune and build lifegain combo with Sanguine Bond, Exquisite Blood, Defiant Bloodlord, and the like
Shutting down your opponents creatures and nonbasic lands for a turn gets Thalias disruptive nature across, while cashing in your own lands for cards gives the Gitrog Monster time to shine
All we need to do is play our creatures, and everything usually takes care of itself from there
The other ability on Liesa is much more control-friendly and heavily enhances removal