I tell you what, I wish all suggestions were like this. For one, this can be put into the game, similar to the other slayer monsters have. Secondly, nothing appears to be overpowered and there are no exaggerated rewards. Thirdly, it confronts the problem of mid-level slayering which can get very stale after awhile. Above all, the idea is unique enough to be worth adding and actually adds a new dimension to the skill and fighting. The Greek style to it can add a lot of extension possibilities whilst not being too farfetched from the rest of the game and I particularly love the encouragement to slay with friends and the obvious need of skill, something in which the game desperately lacks, to kill the monster individually. I hardly ever say this but I would seriously consider suggesting something like this to Jagex. Great idea!