well i have been thinking that there is no hardmode invasion, there is the frost legion but you can only get the summoner on x-mas or if you use cheats, and they dont drop any accesory, weapon etc, so a hardmode invasion could be usefull, i decided to make an invasion called, the alien invasion.

the alien invasion will start by discovering a u.f.o (if you are in outer space long enougt) after that the ship will damage and fall, you will get to it and discover an alien who escaped from a hostile alien invasion who will say to you that this invasion is ready to conquer your world , after that it will appear a message saying "the alien invasion is approaching" , after that lots of aliens and ships will come and start attacking you like a normal invasion, there are 5 types of aliens,a ligth one with plasma pistol 210 of health and is fast, a sniper one which shoots you from a distance he will stay at the border of the screen, if you try to approach to him too much he runs away from you, he has 200 of health and has medium speed, a heavy one, carries a big laser megashark type, it has 270 but is really slow, and a melee one that has a phasesaber and has 230 health, if you manage to beat them, the alien that crashed will move to your town, he will sell you some alien weapons and ammo (kinda like the guns dealer)but also some other alien things like accesories, he also sells special items that will help you get to a space stage.

feel free to change things about this idea, like buffing or nerfing an alien enemy, another thing for the alien to sell, also help with sprited, quotes or others,