mtg whenever opponent draws card Consecrated Sphinx |4UU| Creature Scrawling Crawler (Foundations Promos)

As the 2nd true flip Planeswalker on both sides (Garruk Relentless into Garruk, the Veil-Cursed was the first), Arlinn offers a lot of options

Draw engines and cantrips are super common in a lot of decks in Commander

Card Name Mana Cost Type Enchantment Rarity Rare rules Text Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card

They also get the more scarce in Magic instances of removing counters or dealing out -1/-1 counters

The key here is not to be purely interactive and reactive, which isn't what you want to do in Modern anyway