First Contact is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Mill four cards. You may put a permanent card from among them into your hand. If this spell is the first spell you've cast this game, you gain 2 life. (To mill four cards, put the top four cards of your library into your graveyard.)

How it works : First Contact

Original English text — Wizards of the Coast / Scryfall

No additional ruling has been published for this card.

Interactions with other cards

These cards' text mentions First Contact.

Overseer of Vault 76

First Contact — Whenever Overseer of Vault 76 or another creature you control with power 3 or less enters, put a quest counter on Overseer of Vault 76. At the beginning of combat on your turn, you may remove three quest counters from among permanents you control. When you do, put a +1/+1 counter on each creature you control and they gain vigilance until end of turn.