Tocasia, Dig Site Mentor 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

Creatures you control have vigilance and ": Surveil 1." (To surveil 1, look at the top card of your library. You may put that card into your graveyard.) , Exile this card from your graveyard: Return any number of target artifact cards with total mana value 10 or less from your graveyard to the battlefield. Activate only as a sorcery.

Complete guide

Tocasia, Dig Site Mentor is a powerhouse for artifact-based strategies and graveyard manipulation. This legendary artificer provides your entire board with defensive utility and the ability to filter your deck, all while waiting in the graveyard to orchestrate a massive late-game comeback.

Dual-Purpose Utility

Tocasia grants two distinct abilities to every creature you control: vigilance and an activated ability to surveil 1. Because your creatures have vigilance, they can attack without tapping, leaving them available to tap for the surveil ability during your opponent's turn or after combat. This ensures you are constantly sculpting your hand and filling your graveyard for future plays.

The Grand Excavation

While in the graveyard, Tocasia offers a high-cost activated ability that can turn the tide of a game. By paying eight mana and exiling her, you can return any number of artifact cards from your graveyard to the battlefield, provided their total mana value does not exceed 10. This ability is restricted to your main phase when the stack is empty, functioning at sorcery speed.

Mastering the Mana Value

A common mistake is miscalculating the total mana value for the exile ability. You must target the artifacts as you activate the ability, and their combined mana value must be 10 or less at that moment. If a targeted card leaves the graveyard before the ability resolves, the remaining targets will still return, provided the total mana value was legal when the ability was put on the stack.

Strategic Implementation

Tocasia is best utilized in decks that benefit from filling the graveyard quickly. Use the surveil ability to dump powerful artifacts like Solemn Simulacrum early on. Even if your creatures are small, the ability to look at the top card of your library helps you find the lands or answers you need while preparing for Tocasia's final, explosive resurrection effect.

Interaction examples

The Vigilant Scout

Eternal Witness

With Tocasia on the battlefield, your Eternal Witness gains vigilance. You can attack an opponent, and because it doesn't tap to attack, you can then tap Eternal Witness to surveil 1 at the end of your opponent's turn, helping you find more cards for Eternal Witness to eventually recover.

Value Excavation

Solemn Simulacrum

If Tocasia and two copies of Solemn Simulacrum are in your graveyard, you can pay the exile cost of Tocasia to target both golems. Since each Solemn Simulacrum has a mana value of 4, the total is 8, which is under the limit of 10. Both enter the battlefield, allowing you to search for two basic lands.

Guide written with AI from the official text and rulings. Official English text prevails.