A truly MASSIVE TNT cannon.
I'm thinking the sort of cannon where you look around at the landscape beforehand, think to yourself "nope" then push a button and kick back and watch the final doom of said landscape unfold.
Join the war against things.
Or (if you want me to be boring and relevant), get a rapier with an awakened draconium blade, bedrock handle (need to add Rotarycraft for this) and thaumium/paper crosspiece.
Top tier damage, fast attack speed, infinite durability, extra modifier. Use one modifier slot for lapis to get looting III then quartz for the rest. You're suddenly a whirling dervish of murderous damage :3