If you are at 12 runes and cannot channel for your turn, do you draw one more card?

Ruling: No, you do not draw a card if you cannot channel. You simply do not channel at all.

Nuances:

• Some learn-to-play videos incorrectly showed this rule, but it was a mistake
• Ramp spells that draw cards when you can't channel may create confusion, as they seem like reminder text for channeling, but this is not how the base channeling rule works