Delver of Secrets is no stranger to Modern. Some crazy versions went so far as to sideboard the Gifts Ungiven / Unburial Rites package in order to dodge removal that dealt with small creatures. With Gifts Ungiven, you can choose to search for only two cards, forcing your opponent to put them both in your graveyard. If you have Unburial Rites and a huge creature, you'll likely be in pretty good shape.
Some experimented with using that package maindeck, but it didn't last long. We've seen some U/R Delver decks do pretty well on Magic Online recently, but it hasn't ever been as close to dominant as one would assume Delver would be in Modern. Perhaps that backup plan is exactly what it needs. Oddly enough, I would have expected Griselbrand to be the monster of choice, since the package is at its best against midrange strategies. You can't really go wrong with Iona, Shield of Emeria though.
The rest of the deck is pretty standard Delver fare, although the sideboard has a few other surprises, mainly Thoughtseize. With access to eight or more fetchlands, it's not difficult to splash anything, and Thoughtseize covers your bases in a wide open format like Modern.
- 4 Delver of Secrets
- 2 Grim Lavamancer
- 4 Snapcaster Mage
- 4 Young Pyromancer
- 1 Iona, Shield of Emeria
- 2 Vendilion Clique