To get a flamethrower follow these steps: 1.Throw one emerald below a villager he'll turn it to something.2.Then get 121 gold ingots and go into his interface and if you scroll down you'll find a trade that needs 45 gold ingots.3.Then do that trade and summon the Flamethrower.4.Place a coal block on top of it.5.Go back to the villager get the Rotate trade.This is used how to rotate the flamethrower.6.Summon it on top of it and BOOM!7.To use the cannon find the mark and another trade I forgot which one :( Then summon the mark where you want the cannon to shoot.Then throw 8 TNT at the cannon.Then throw 1 piece of gunpowder at the cannon and KABAM!It'll launch where you placed the mark.Good luck command engineers :)