Reality Acid: Remove any permanent you want. Take away their mana, their combo pieces, their threats, whatever. With the Cloudstone+Anvil this card goes absolutely nutballs, Just bounce it against any of your other echantments and clear the board.
Spreading Seas: Card Advantage and Land Disruption, limit their splash color, turn of utility lands and get ahead. The potency of this card is greatly amplified by the bouncing, since you'll draw several cards and can move it around when a better target comes out, for example if it becomes more important to limit another color than the one you started with. Can also be used to give yourself more islands for Vedalken Shackles.
Tectonic Edge: Rounding out our land disruption package, good with the seas because you can disrupt the first few lands and then use this to keep the 4th away. Very relevant that you can hold priority to trigger several of these against 4 lands, to get around the 4 land limit and get them down from 4 to 2.
Demonic Pact: The embodiment of risk vs reward, this card fits very well in this deck and opens up a flexible suite of value plays. Bounce it to keep it fresh and your opponent will be hard pressed to play his threats into the 4 damage or keep it in hand into the discard, makes for the perfect card to induce misplays, and when neither of those apply you just pull ahead with the card draw. It is quite important to plan ahead so you can bounce it in time, but sometimes it's correct to just jam this in and take the risk even without bounce in hand, especially if you can anticipate either winning or losing within 3 turns anyways, which actually isn't unusual at all. This card should be sided out/not played against any kind of mindslaver effect as they can just chose "lose the game".
Doomwake Giant: Big nasty repeatable board sweeper. With this in play and some bounce going some go-wide decks just fold. Great against elves, goblins and what have you. Gets around hexproof, indestructible and protection too.
Trial of Ambition: Forced sacrifices are great, and this one works really well in this deck. It can be important to stack the triggers correctly when casting this in conjunction with doomwake giant or to bounce reality acid if it's on a creature. You want the trial trigger at the bottom of the stack so they don't get the chance to sac a creature that will die anyways to the other effects.
Vedalken Shackles: Steal their dudes. This card is in the maindeck mainly because it's the most generally useful 3 CMC artifact I found for this important slot, which is being the 3rd target for Trophy Mage so they don't become dead draws after securing cloudstone and anvil. I really like the shackles in a lot of matchups, but it is the most obvious card to side out for any of the more specific sideboard hate artifacts.
Brain Maggot: Hand disruption, takes any nonland card and serves as another echantment creature for consistency. Bouncing this can be useful to switch cards when the first is no longer a problem to deal with.
Inquisition of Kozilek: More hand disruption, this deck needs a little setup and a turn 1 IOK can buy that time for you in a lot of games.
