This is a very good guide and includes a lot of the subtle things that separate a good from a great Gazlowe. I may go back to Extra TNT at lvl 1. I used to take it, then switched builds to take the bonus mana, then switched again for the reduced cooldowns. I find it's just too easy for enemies to dodge the stun unless you're doing the wombo combo. I will say that I almost never have mana issues using Break it Down and Reduce/Reuse, and the number of turrets you can put in a field of death...