Drown in the Loch is an extremely powerful card from Throne of Eldraine. While at first glance this may look like a card only to slot into a mill deck, it's actually just a very powerful and flexible card in a regular control deck.
Dimir Control with Drown in the Loch
4 Drown in the Loch 3 Witch's Vengeance 4 Vantress Gargoyle 4 Murderous Rider 2 Ritual of Soot 3 Chemister's Insight 1 Bond of Insight 2 Enter the God-Eternals 4 Thought Collapse 4 Thought Erasure 4 Discovery/Dispersal 4 Watery Grave 4 Submerged Boneyard 9 Swamp (339) 8 Island (335)
It's difficult to build a control deck before day 1 of the metagame, but this shell gives us a rough idea of what is possible. Let's examine the individual cards from Throne of Eldraine and how some of the older cards fit in.
Drown in the Loch is an incredibly flexible and powerful card for only two mana. A control deck is built entirely around interacting with your opponent's gameplan, so you will be trading pieces of cardboard and filling your opponent's graveyard naturally throughout the course of the game. This can be used as a normal removal spell early on as long as it's not your literal only spell, and it becomes a hard counterspell in the late game.
Vantress Gargoyle is an awesome card that we've been including in a lot of our brewing, though in a lot of cases simply due to its artifact type. However, it is appealing in this strategy just due to its above-rate stats. It serves as an extremely efficient blocker in the early game. It can also turn the corner quickly and let this deck close out games once you've contained their start. Its passive ability to mill each player can benefit you in small ways such as turning Chemister's Insight face up, but it also gets Drown in the Loch online much faster and more reliably.
Similar to Drown in the Loch, Witch's Vengeance is a card that might get unfairly typecast at first glance before taking time to consider its true strength. What might seem like a sideboard hate card, it's actually just an efficient removal spell with upside. While three mana for a conditional 1-for-1 is not the best exchange, it's still passable. However, the Standard card pool is very limited and many creatures naturally overlap in types, which could mean an easy 2-for-1. The massive upside becomes evident when we consider that many of the most aggressive decks in the format will be tribal, and our cheap removal spell is upgraded into a one-sided sweeper.
Murderous Rider is likely one of the best cards in Throne of Eldraine. As many writers will tell you, this card is basically Hero's Downfall that draws you a card. Having a card that was already a Standard staple get a huge upgrade is an obvious inclusion in most decks that can cast it. The creature half is not the greatest card to draw, but it's nice that it offsets its own life loss.
While Thought Erasure is a staple that needs no further justification, Enter the God-Eternals and Thought Collapse are additional ways to fill the opponent's graveyard a bit. We probably don't need all of these, but some copies will end up included.
Bond of Insight is another cute card that is essentially a draw-2 that has the passive upside of milling your opponent a bit for Drown in the Loch and Vantress Gargoyle.
We may have gone too deep on the passive milling plan, and find that Drown in the Loch and Vantress Gargoyle can be supported just by the normal gameplan of a deck that resembles this Dimir Control deck by Mark Jacobson. Regardless, these cards are so powerful that if a Dimir control shell can be built to attack a specific metagame, we believe it has a real chance to be a contender.