Take a look at three of the top decks from the Vintage Challenge with Islandswamp!
https://www.mtggoldfish.com/articles/vintage-101-mana-drain-returns
The Triumphant Return of Mana Drain
A few articles ago, in the wake of the third and most recent Gush restriction, I posited that perhaps we might see a resurgence of Mana Drain in contemporary Vintage. It appears that is exactly what is happening, although I certainly wouldn't say that Mana Drain is overly dominant. We went from a situation where very few successful decks wielded Mana Drain to one where several different kinds of Drain decks have had breakout performances. A few weeks ago Grixis Thieves won the Power Nine Challenge (although the top-performing Shops deck from the Swiss portion dropped from the event early). Now, this past Saturday we had another Drain deck take down the event as well as a second deck featuring Drains and Gifts Ungiven in the Top Eight.