Battle Trance

Battle Trance is a 0-cost Ironclad skill that draws 2 cards (3 upgraded) but prevents drawing more cards for the rest of that turn. The restriction means any additional draw effects or relics that would trigger won't function that turn. Even so, drawing 2-3 free cards is excellent value, and in decks with few or no other draw effects, the restriction barely matters.

Battle Trance is particularly strong as a hand-size booster before Fiend Fire, or as an early-turn draw to find your key cards quickly. The 0-cost means you're getting cards purely for free. In decks without many draw effects, the downside is nearly irrelevant. Upgraded to 3 cards, it's one of the best free draws in the game for the Ironclad.