I hated the destroyer cuz he would like wipe out 50% of my town population so here are some recommendations:
Hardmode Armor- hardmode armor such as palladium would spawn random lasers towards you if you take damage, or that beetle armor spawns beetles that have you take less damage
Weapons- Idk my first weapon but I like the terra blade
Gear- Personally, I like warding upgrades on these things because it gives me more defense but theres an upgrade that gives you like +4 damage
Gear- Continued, carry multiple potions i guess
Tactics- Dont get surrounded, keep moving, also DO NOT spawn the destroyer near your town!!!!, spawn it in an arena or somewhere unpopulated