If you’ve been watching mann_und_mouses’ stream, you may already know the answer to this question. The data seems to suggest that 2 is probably fine. 3 might be too many based on the rest of your deck construction. At 4-5 Mortars, you start to risk losing board position as your opponent plays units with <4 toughness. We do need more data though, so If you happen to draft 4 or more make sure to submit that draft!