Ambush Viper 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

Flash Deathtouch

How it works : Ambush Viper

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 Ambush Viper.

Jessie Zane, Fangbringer

Deathtouch When Jessie Zane enters and whenever you cast a Snake spell, conjure a card named Ambush Viper into the top six cards of your library at random. It perpetually gains "When this creature enters, draw a card."