Looks decent so far, but if you don't mind a long post, I have some suggestions to make.

For starters, you have too much land, and too many that enter play tapped. I've been good with six scry lands, and 26 lands in my deck. Pearl Lake Ancient should also be replaced by Spellheart Chimera and Prognostic Sphinx. They work really well together, and the shpinx will help you draw your best spells. Two copies each should be enough. If you're still worried about your creatures getting countered, or the chimera getting burned, Swan Song and Negate are great counters. And the bird token is even less of a problem here, since the chimera has trample, and both creatures can block it without fear of dying.

For instants and sorceries, you need more removal like Bile Blight, which is especially powerful against decks with Goblin Rabblemaster or Brimaz. Lightning Strike and Magma Jet are great for taking out morph creatures and small creatures, saving your Hero's Downfall for 'walkers and fatties. Drown in Sorrow and Anger of the Gods are also good for removing multiple creatures, so you should try to work some of those in as well. This will also fuel delve faster, make your chimera bigger, and give you more creatures to bring back with Liliana Vess. Finally, with Dig Through Time and Steam Augury you really don't need Interpret the Signs. However, Jace's Ingenuity might be better, as it will usually give you more cards than the augury, without the drawback of losing a few.

For your walkers, I would keep Liliana Vess, and replace Chandra, Pyromaster with either Jace, the Living Guildpact or Ashiok, Nightmare Weaver, as both get you card advantage and have devastating ultimates. On a side note, Despise has often been a dead draw for me outside of the early game, but if it's working for you, keep it. Otherwise, I wouldn't change too much else about the deck. Good luck, and have fun playing!