Delver is an archetype which has had it's time in the spotlight time and time again. It's always going to be live in Legacy and Modern. And here's just another Delver Variant.
Creatures
Really just threats. Enough said.
Geist of Saint Traft: Very good creature overall. Attacks for 6 and with hexproof to make so it doesn't die to Lightning Bolt or Path to Exile.
Delver of Secrets
: Turn 1 1/1. Turn 2 3/2 with FLYING
Monastery Swiftspear: 1/2 Haste creature that pumps itself every time you cast a noncreature spell. Overall solid and can potentially avoid a Lightning Bolt.
Young Pyromancer: If you can untap with Young Pyromancer it can mean game over in some situations.
Snapcaster Mage: If you play blue, you play Snapcaster Mage. Opens up your grave.
Cantrips
The deck literally runs off of these. These are the main fuel for your Prowess creatures.
Serum Visions: Best cantrip in Modern. Great with Delver of Secrets
Gitaxian Probe: FREE INFORMATION AND DRAW A CARD. Too good to turn down.
Removal
Say bye to creatures and some burn to the face late game, or when going for the kill.
Lightning Bolt: One of the best cards in Modern. 3 damage to the face or take out most of the creatures played in Modern.
Path to Exile: 1 Mana "Exile target creature and one land doesn't hurt."
Forked Bolt: Very versatile removal spell and does a lot more than you would think at first glance.
Lightning Helix: Great in a race and against burn. Post board against burn with Soulfire Grand Master it becomes a 6 point life gain and probably game over.
Electrolyze: Amazing tempo and draws you a card. Worst case scenario you cycle it to your opponent's face.
Counterspells
Stuff to stop your opponent or put them behind.
Remand: Put your opponent behind and drawing a card is always great. Also you can remand your own spell sometimes just to get card advantage.
Spell Pierce: A lot of turn 1 plays are noncreature spells, so why not.
Spell Snare: Counters a lot of stuff in modern for 1 Mana. Great Counterspell.