The Boss slayer task would be a good idea, but with limited bosses, for example it could easily ruin Corporeal beast, and many people would farm these tasks, so maybe there should be a limit on it, for example you may get the boss task once a day, in order to prevent bosses to be "overfarmed".
Maybe you could give the abyssal head an other function besides being a trophy, for example exchanging it for some xp in for example slayer, or construction. This could be a solution for all heads tho.
And for last, i am not sure wether private rooms for the upcoming bosses are an option, but i think it should be considered since Kraken may be slain in private, and the new bosses require lower slayer level, which means more adventurer will kill them.
16-May-2015 22:19:12