Use pathing to path monsters into them, and use buildings to make the monsters closer. Useful versus Zafreeti boosted monsters. As the name says, heavy traps. We know that this works with D.A.V.E.s, Champions and other strong monsters. They can't be countered by using weak monsters with Zafreeti or whatever because it would only explode when stronger monsters trigger them but it causes splash damage to nearby monsters. You therefore need to place them more strategically. This is best used with THDT/SDT for 100% efficient performance of the heavy traps and you know how and why so there's no need for further explanation. But in case you don't, you could check it out here. Also, placing 3 heavy traps together will make enough fire power to destroy D.A.V.E units and even Zafreetis that are supporting it.