Card

Teferi's Ageless Insight

Mana cost {2}{U}{U}

If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Part of 67 known combos, one of them two-card. 3 official rulings.

Bracket

B1 Exhibition — Not in the same deck as its two-card combo partner: Peer into the Abyss
B2 Core — Not in the same deck as its two-card combo partner: Peer into the Abyss
B3 Upgraded — allowed: Its two-card combos are not early, which Bracket 3 allows
B4 Optimized — allowed: No restriction beyond the banned list
B5 cEDH — allowed: No restriction beyond the banned list

Bracket: Lotus Vault analysis, with Commander Spellbook flags

67 known combos, one of them two-card.

2020-06-23 · Wizards of the Coast
If two or more replacement effects would apply to a card-drawing event, the player drawing the card chooses the order in which to apply them.
2020-06-23 · Wizards of the Coast
Because Teferi's Ageless Insight is legendary, it's unlikely that one player will control two. However, if that happens, each card that player would draw after the first will result in four cards being drawn. If they control three, they draw eight cards, and so on.
2020-06-23 · Wizards of the Coast
If a spell or ability causes you to put a card into your hand without specifically using the word "draw," it's not a card drawn.

Rulings: Scryfall · Wizards of the Coast