Patch 'n mod

[Alneyan]

Technically, you can enforce "no hoarding" from a game, as item modding should now be available. Make clams and the whole thing require 5 Nature and 5 Air, and you will be virtually rid of them (summon spells are easier to remove from the picture).

The other way is, as usual, to have a devoted host (and host only) check the game every single turn. This would, however, not exactly be feasible in this case, unless you only have a few players in the game.