Make upgrades like shaped explosives, or elemental tnt, or increased radius, increased damage, a knockback effect, make it do less damage in general, or just to your drone, make it's damage stack even better with other tnt, almost like a multiplicative effect.
Make upgrades like shaped explosives, or elemental tnt, or increased radius, increased damage, a knockback effect, make it do less damage in general, or just to your drone, make it's damage stack even better with other tnt, almost like a multiplicative effect.