Lodestone Golem

• WWizards of the Coast2010-03-01
  Official Ruling
  When determining a spell's total cost, effects that increase the cost are applied before effects that reduce the cost.
• WWizards of the Coast2010-03-01
  Official Ruling
  The ability affects the total cost of each nonartifact spell, but it doesn't change that spell's mana cost or mana value. The extra mana also doesn't change how many times you kicked the spell or what the value of X is (if applicable).
• WWizards of the Coast2010-03-01
  Official Ruling
  The ability affects each spell that's not an artifact spell, including your own.

Rulings via Scryfall

• WO
  Wizards of the Coast2016-04-04

  Lodestone Golem was restricted in vintage on April 4, 2016. We continue to see an imbalanced metagame, with Mishra's Workshop–based decks significantly overrepresented. Lodestone Golem leads to some of the less-interactive games. We are hopeful that limiting Workshop decks to one copy of the card leaves the deck at an appropriate strength, and for that reason, Lodestone Golem is restricted. Source: https://magic.wizards.com/en/news/news/banned-and-restricted-announcement-2016-04-04