Tunguska Meteor/Mega Meteor/whatever: Rarely, you can get a single large meteor that completely obliterates everything in a large AOE.

Strange Rod: Occassionally, You can get a rod that flies right through a galaxy in any cardinal direction, instakilling everything in its path.

Star Cell: At about the same rarity as a random Dragon spawn, you can get a single circular cell that "latches" onto a star system, after 4 seconds rendering it neutral and disrupted for 15 seconds, and destroying any artifacts and nullifying wealth. Once it absorbs 2 star systems, it splits into 2, starting the cycle anew. They die out without food eventually, to prevent races being spawncamped by cells.

Insanity Parasite: Appears very rarely. Flimsy, but it can latch on to star systems, like the Star Cell, but it stays latched for a minute. and a half. If it stays latched for a minute, the race state changes to ALL_WILL_BE_ASHES. 

What do you think?