Creatures - 9
2 Chasm Skulker
3 Giant Scorpion
2 Talrand, Sky Summoner
2 Dinrova Horror
Other Spells - 27
3 Ulcerate
4 Voyage's End
4 Think Twice
3 Negate
3 Nullify
3 Dissolve
3 Mind Rot
2 Inspiration
2 Flesh to Dust
Land - 24
4 Dimir Guildgate
13 Island
7 Swamp
Thought Drain plays a lot like Wall of Denial, but with black for some discard, spot removal, and Dinrova Horror. With the creature kill spells (and Giant Scorpions), you can be a little more conservative with your counters. Chasm Skulker and Talrand are perfect finishers in a blue based control deck with counterspells. This allows you to play them turns 5-7 while holding mana open for protecting them with counterspells.
Don’t be fooled by the casting cost, Mind Rot is more of a mid to late game spell. Ideally, you want to play it when your opponent only has 2-3 cards left. Use the card draw when you can to keep your hand full of control spells. Dinrova Horror can answer a threat on the board, and if your opponent’s hand is empty, they’ll have no choice but to discard the card you bounce, which gives this U/B control deck an out to any artifacts and enchantments that happen to resolve. And while a 4/4 isn’t the biggest or quickest way to take out your opponent’s life total, it does get the job done.