@Zax: I made a mistake.  Last Thoughts is obviously not usable with Isochron Scepter, and I am dumb.  As such, you may find it more useful to sideboard something in, or even replace them with Laboratory Maniac, which gives you another win condition (draw all your cards), and safeguards you from accidental self-mill loss.  Depends on your preferred playstyle though; Cipher can still be useful, especially when combined with Echo Mage.

To make this a 66-card, remove the Echo Mages and 1 Island.  I think it's better as a 69er though ;)

Edit: The more I think about it, the more I feel like Last Thoughts doesn't really fit this deck.  I recommend replacing it with another couple Scepters.  Then you can decide how many Scepters you actually need, and play with your sideboard to get it right.

@Zax: Originally, I had the Echo Mages in the sideboard, but I removed a Kargan and a Cryptologist to swap them in.  Why?  I went and checked the rulings on the card...

"Echo Mage's last two activated abilities can target (and copy) any instant or sorcery spell, not just one with targets. It doesn't matter who controls it."

Thermokarst?  I'll take that.  Oh, is that a Demonic Tutor?  Why, I do believe I will now be searching for two cards, thank you. 

But it gets better:

Did you want to counter that spell?  Excuse me while I copy your counterspell and use it to counter itself.

Oh yes:

"Each copy will then resolve like a normal spell, after players get a chance to cast spells and activate abilities. Each copy resolves before the original spell does."

And you can even do this with 2 copies without it being illegal:

"Each copy will have the same targets as the spell it's copying unless you choose new ones. You may change any number of the targets, including all of them or none of them. If, for one of the targets, you can't choose a new legal target, then it remains unchanged (even if the current target is illegal)."

This card takes all the annoying things Erik can throw at you and sends them right back.  Although he's made his deck just slightly less susceptible to this now that it, you know, actually has creatures.