This deck is a revision of an old attempt to build a deck that would very quickly ramp up to threats like Worldspine Wurm and Craterhoof Behemoth. The addition of Garruk, Caller of Beasts means big threats like Worldspine Wurm can show up as early as turn 3 (sometimes followed by another big threat on turn 4). Of course, some hands you'll just have a turn 3 Primeval Titan, which, on its own, can lead to a hard cast turn 4 Worldspine Wurm anyway (Titan makes it easy to assemble Tron!).
Cards like Worldspine Wurm and Protean Hulk provide some extra protection against removal (particularly mass removal), and Craterhoof Behemoth can win a game out of nowhere.
A quick rundown of the sideboard:
Creeping Corrosion
is for destroying annoying equipment and completely screwing Affinity/Robots.
Unravel the Aether is for the same, plus it deals with Keranos, God of Storms.
Cavern of Souls is for resolving your big creatures through counterspells. If you hit all 3 Caverns (or fetch them with Titans), name Giant, Wurm, and Beast.
Quicksilver Amulet is for high-removal matchups (where elves may not survive long enough to be useful), as well as for control matchups (a resolved Quicksilver lets you flash in your big threats at any time for 4 mana!). Depending on the control matchup, though, you may not need the Amulet, as Cavern of Souls makes your big creatures uncounterable anyway.
Summoning Trap is also for control or tempo-control matchups (like any Delver of Secrets
variant). Just watch them Mana Leak your Elvish Archdruid, only to face a free Summoning Trap that could find something big and nasty (turn 2 Worldspine Wurm, anyone?).
Terastodon is for removing problem permanents that the deck otherwise can't handle (though sometimes, turning 3 of your own lands into elephants right before dropping Craterhoof Behemoth isn't so bad either).
The deck is very powerful and relatively consistent, but any suggestions to improve it are welcome.
