Tamiyo's Logbook — ruling 1

The cost reduction of the activated ability applies only to the generic mana component of the activation cost. It can't reduce colored mana costs. Even if you have five or more artifacts, it still costs {U} to activate.

Tamiyo's Logbook : règles, fonctionnement et interactions (MTG)

Tamiyo's Logbook 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

, : Draw a card. This ability costs less to activate for each other artifact you control.

Complete guide

Tamiyo's Logbook is a powerful artifact for blue mages who love to tinker with machines and treasures. This Book artifact rewards you for building a vast board of trinkets by making its card-drawing ability significantly cheaper. Let's dive into how you can use this logbook to keep your hand full throughout the game.

A Discount for Every Artifact

The primary function of Tamiyo's Logbook is to draw cards, but its true strength lies in its cost-reduction ability. For every other artifact you control, the generic mana cost of its activated ability decreases by {1}. Note that this count does not include the Logbook itself, so you will need at least five other artifacts to reach the maximum possible discount.

Step-by-Step Activation

To use the ability, first check how many other artifacts you currently control. Subtract that number from the {5} generic mana cost. Then, pay the remaining mana (which will always include at least {U}) and tap the Logbook. Once the cost is paid and the ability is on the stack, it doesn't matter if your other artifacts leave the battlefield; the ability will resolve and you will draw your card.

Important Cost Limitations

A common mistake is assuming the ability can become free. However, cost reduction only applies to the generic mana component of the activation cost. Even if you control ten artifacts, you must still pay the single Blue mana ({U}) and tap the Logbook to draw your card. Additionally, this effect only reduces the cost of the Logbook's specific activated ability, not other spells or artifacts.

When to Use the Logbook

Tamiyo's Logbook is best utilized in the late game or in decks that generate many tokens, such as Treasures or Clues. It serves as a reliable mana sink during your opponent's end step. By waiting until the last moment, you keep your mana open for counterspells or removal, then use the Logbook to replenish your resources if that mana wasn't needed.

Interaction examples

Building a Basic Discount

Arcane Signet

With Tamiyo's Logbook and Arcane Signet on the battlefield, you control one other artifact. This reduces the activation cost by {1}. Instead of paying {5}{U}, you only need to pay {4}{U} and tap the Logbook to draw a card.

Stacking the Workshop

Arcane Signet

Swiftfoot Boots

If you have both Arcane Signet and Swiftfoot Boots in play along with the Logbook, you now control two other artifacts. The cost is reduced by {2}, meaning it only costs {3}{U} to activate. The reduction scales as your collection of equipment and mana rocks grows.

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

How it works : Tamiyo's Logbook

Original English text — Wizards of the Coast / Scryfall

#1February 4, 2023· Wizards of the Coast
The cost reduction of the activated ability applies only to the generic mana component of the activation cost. It can't reduce colored mana costs. Even if you have five or more artifacts, it still costs to activate.
No other card is named in this ruling.