Against Sanitar, you need to take the counterspell ability - when Sanitar has around 70 knowledge, and we have 120-140, that's when we'll need Nura - we can simply cast the counterspell.
Against Sanitar, you need to take the counterspell ability - when Sanitar has around 70 knowledge, and we have 120-140, that's when we'll need Nura - we can simply cast the counterspell.