They don't melt,but Clops and Havok are in an enclosed area where they don't need to worry about civilians.As they are immune to eachpthers powers they win ala Omniblasts.
The summers brothers are immune to each others powers so havok and cyclops can both start out with an omni directional blast. The concussive force probably wouldnt do too much to colossus but havoks plasma is supposed to rival the surface of the sun in terms of temperature. If somehow wolverine isnt completely out of it they can both continuosly blast at him until he *decides* to die.
Gender: Unspecified Location: REALM OF THE UNDERWORLD
Havok has melted Adamantium wall before protecting the secrets of the weapon x program but I doubt its probably same grade as Wolvie adamantium. Still thats says a lot, dont know how tough Rasputins organic steel is tougher than med to low level grade adamantium..