Major Story Arcs
When Arisen Tyrk was deposed as God-King of the extradimensional Other Realm, he fled through a damaged portal that split him into various fragments. Some of Tyrk's sentient fragments landed on Earth. One fragment became drama professor Harrison Turk and the others plagued the Defenders as the crazed Lunatik vigilantes. These other versions appeared during successive full moons. The first became Lunatik and desired to punish evil but had problems distinguishing right and wrong. The second one exemplified adventurousness, and the third, loyalty. Both admired the original, and helped him in his deeds.
Valkyrie, Hellcat, and Nighthawk eventually defeated the three Lunatiks.
All the versions of Tyrk were eventually brought together and mystically re-merged into Tyrk in the Tunnelworld, where he tried to defeat the powerful Unnameable, and was defeated.
One Lunatik shard somehow avoided merger, and was killed by the cosmic villain Lunatik, because he didn't want anyone else to share his name.
Powers & Abilities
The Lunatiks seemed to have some degree of superhuman strength, speed, and agility--possibly different levels for each one, as one Lunatik contended fairly equally with the very strong Valkyrie, while the others fought the low-level superhuman Nighthawk and the somewhat-enhanced Hellcat.
Regardless of their exact levels, they were all formidable combatants, and carried metal cudgels.