Bastion Inventor — ruling 1

Improvise doesn’t change a spell’s mana cost or mana value.

Bastion Inventor — ruling 2

When calculating a spell’s total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Improvise applies after the total cost is calculated.

Bastion Inventor — ruling 3

Because improvise isn’t an alternative cost, it can be used in conjunction with alternative costs.

Bastion Inventor — ruling 4

Improvise can’t pay for {W}, {U}, {B}, {R}, {G}, or {C} mana symbols in a spell’s total cost.

Bastion Inventor — ruling 5

Improvise can’t be used to pay for anything other than the cost of casting the spell. For example, it can’t be used during the resolution of an ability that says “Counter target spell unless its controller pays {3}.”

Bastion Inventor — ruling 6

If an artifact you control has a mana ability with {T} in the cost, activating that ability while casting a spell with improvise will result in the artifact being tapped when you pay the spell’s costs. You won’t be able to tap it again for improvise. Similarly, if you sacrifice an artifact to activate a mana ability while casting a spell with improvise, that artifact won’t be on the battlefield when you pay the spell’s costs, so you won’t be able to tap it for improvise.

Bastion Inventor — ruling 7

Tapping an artifact won’t cause its abilities to stop applying unless those abilities say so.

Bastion Inventor — ruling 8

Equipment attached to a creature doesn’t become tapped when that creature becomes tapped, and tapping that Equipment doesn’t cause the creature to become tapped.

Bastion Inventor : règles, fonctionnement et interactions (MTG)

Bastion Inventor 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

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .) Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Complete guide

Bastion Inventor is a powerful late-game threat that leverages your artifact-heavy board to enter the battlefield early. Once it arrives, its Hexproof ability ensures it remains a persistent problem for your opponents, immune to targeted removal. Mastering the Improvise mechanic is key to maximizing the efficiency of this Vedalken Artificer.

What It Does

Bastion Inventor has two primary keywords: Improvise and Hexproof. Improvise is a static ability that acts as a payment method for the generic portion of the spell's cost, allowing you to tap artifacts instead of spending mana. Hexproof is a keyword that protects the creature from being the target of spells or abilities controlled by your opponents, forcing them to rely on non-targeted board wipes or combat to remove it.

How It Resolves Step by Step

When you cast Bastion Inventor, you first announce the spell and place it on the stack. You then calculate the total cost, which is {5}{U}. Before paying, you activate any mana abilities you need. Finally, you pay the cost: you must spend one Blue mana ({U}), and you can pay the remaining {5} generic mana by spending mana, tapping untapped artifacts you control via Improvise, or a combination of both. Once the costs are paid, the spell is officially cast.

Common Mistakes

A common error is trying to use Improvise to pay for the colored {U} requirement; Improvise only applies to generic mana. Additionally, remember that you cannot tap the same artifact for both a mana ability and Improvise. If you tap an artifact for its own mana ability, it is already tapped by the time you reach the payment step where Improvise occurs. Also, note that equipment and tokens (like Treasure or Food) can be tapped for Improvise without losing their functionality or affecting the creatures they are attached to.

When to Play It

Bastion Inventor is best played when you have established a board of non-creature artifacts or utility creatures that don't need to attack. Because it has Hexproof, it is an excellent target for Auras or Equipment, as your opponent cannot easily disrupt your strategy with targeted 'bouncing' or 'kill' spells.

Interaction examples

Scaling Power with Psychosis Crawler

Psychosis Crawler

If you control Psychosis Crawler, you can tap it to help pay for Bastion Inventor using Improvise. Even though Psychosis Crawler becomes tapped, its static ability defining its power and toughness based on your hand size remains active, and its triggered ability will still fire whenever you draw a card.

Navigating Hullbreaker Horror

Hullbreaker Horror

If an opponent controls Hullbreaker Horror, they may try to return Bastion Inventor to your hand when you cast another spell. However, once Bastion Inventor has resolved and is on the battlefield, its Hexproof ability prevents Hullbreaker Horror's triggered ability from targeting it. Note that if Bastion Inventor is still a spell on the stack, it does not have Hexproof yet and can be returned to your hand by the Horror's first mode.

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

How it works : Bastion Inventor

Original English text — Wizards of the Coast / Scryfall

#1February 9, 2017· Wizards of the Coast
Improvise doesn’t change a spell’s mana cost or mana value.
No other card is named in this ruling.
#2February 9, 2017· Wizards of the Coast
When calculating a spell’s total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Improvise applies after the total cost is calculated.
No other card is named in this ruling.
#3February 9, 2017· Wizards of the Coast
Because improvise isn’t an alternative cost, it can be used in conjunction with alternative costs.
No other card is named in this ruling.
#4February 9, 2017· Wizards of the Coast
Improvise can’t pay for , , , , , or mana symbols in a spell’s total cost.
No other card is named in this ruling.
#5February 9, 2017· Wizards of the Coast
Improvise can’t be used to pay for anything other than the cost of casting the spell. For example, it can’t be used during the resolution of an ability that says “Counter target spell unless its controller pays .”
No other card is named in this ruling.
#6February 9, 2017· Wizards of the Coast
If an artifact you control has a mana ability with in the cost, activating that ability while casting a spell with improvise will result in the artifact being tapped when you pay the spell’s costs. You won’t be able to tap it again for improvise. Similarly, if you sacrifice an artifact to activate a mana ability while casting a spell with improvise, that artifact won’t be on the battlefield when you pay the spell’s costs, so you won’t be able to tap it for improvise.
No other card is named in this ruling.
#7February 9, 2017· Wizards of the Coast
Tapping an artifact won’t cause its abilities to stop applying unless those abilities say so.
No other card is named in this ruling.
#8February 9, 2017· Wizards of the Coast
Equipment attached to a creature doesn’t become tapped when that creature becomes tapped, and tapping that Equipment doesn’t cause the creature to become tapped.
No other card is named in this ruling.