Here are the 3 Mithril Spellstone cards added to the Warrior class from the Kobolds and Catacombs expansion.
You upgrade the card when you equip a weapon giving you better value for the mana cost each time.
They then summon the following Mithril Golems:
Lesser Mithril Spellstone – Summon one 5/5 Mithril Golem
Mithril Spellstone – Summon two 5/5 Mithril Golems
Greater Mithril Spellstone – Summon three 5/5 Mithril Golems
