Powerstone Engineer — ruling 1

Powerstone tokens are a kind of predefined token. Each one has the artifact subtype "Powerstone" and the ability "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell."

Powerstone Engineer — ruling 2

You can use the {C} added by a Powerstone token on anything that isn't a nonartifact spell. This includes paying costs to activate abilities of both artifact and nonartifact permanents, paying ward costs, and so on.

Powerstone Engineer — ruling 3

Although all the cards in The Brothers' War that create Powerstone tokens create a tapped Powerstone token, entering the battlefield tapped isn't part of the token's definition. Notably, if you create a token that is a copy of a Powerstone token, the token copy won't enter the battlefield tapped.

Powerstone Engineer : règles, fonctionnement et interactions (MTG)

Powerstone Engineer 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

When this creature dies, create a tapped Powerstone token. (It's an artifact with ": Add . This mana can't be spent to cast a nonartifact spell.")

How it works : Powerstone Engineer

Original English text — Wizards of the Coast / Scryfall

#1October 14, 2022· Wizards of the Coast
Powerstone tokens are a kind of predefined token. Each one has the artifact subtype "Powerstone" and the ability ": Add . This mana can't be spent to cast a nonartifact spell."
Card named in this ruling
Powerstone
#2October 14, 2022· Wizards of the Coast
You can use the added by a Powerstone token on anything that isn't a nonartifact spell. This includes paying costs to activate abilities of both artifact and nonartifact permanents, paying ward costs, and so on.
Card named in this ruling
Powerstone
#3October 14, 2022· Wizards of the Coast
Although all the cards in The Brothers' War that create Powerstone tokens create a tapped Powerstone token, entering the battlefield tapped isn't part of the token's definition. Notably, if you create a token that is a copy of a Powerstone token, the token copy won't enter the battlefield tapped.
Card named in this ruling
Powerstone