Take out an ad during the Superbowl...oh wait....nevermind.
IF, and that's a giHUGEically big "If", there are the ducats for a tv commercial, then Cartoon Network is pretty much the only place to go.
Yes, during Big Bang Theory also. [EDIT] OO, and during Game of Thrones and Spartacus: Venegence...or whatever it's called.[/EDIT]
But I think getting a solid 30 second spot in on CN during Stars Wars: Clone Wars, Young Justice (is that still running in the states? I hope so. I really enjoyed it), Wolverine and the X-Men or WHATEVER comic-based show is big at the time would be the biggest boon fer the buck.
Probably, seems to me in this day and age, it's goign to be a wholely interweb campaign. Web ads and vid's on sites...well, quite like this one

and the plethora of other RPG themed, Comic-themed, Fantasy-themed sites.
Make deals (and PAY) for web banner ad space on third party publisher sites, forums, blogs, etc.
Podcasts, obviously...anywhere you can get 'em.
For Print ads...taking out quarter- or half-page space in whatever mag's exist at the time, promotional materials, posters, stand-ups, "handouts" (which no one actually "hands out" anymore but they can be left on the counters for people to take), etc. to any and every comic-book, gaming shop and toy store in the country.
A series of "Collectable" promotion pieces (with stellar art work) of limited run for the die-hard collectors out there....maybe even a deal with Magic:TG for a limited run of 5e-themed cards to play a certain amount of the game.
Heavy presence at whatever Con's are in the preceding...say 6 months prior to release and the year following.
I think that's about all we can expect. But, make no mistake, the web-advertising will FARRRR outweigh anything you see on tv or in print.
--SD