Easy Way to get to get rid of Bone Dragons?

[Fatt_Shade]

First of all your take your rage somewhere else, this is forum for tactical turn based game, not fps where everything happens in 0,1 second.
Second you play impossible setting and want `easy` way to defeat enemy stacks ?
Third you didnt provide any important info about your hero class/army/items/available spells and lvl`s . . . Against bone dragons plague wont work, so BEST (not easy) way is spell defenseless and or fire breath on your best dmg unit. Their fire resistance is low so all fire based spells for pure spell dmg mage class is also good way. One option is to start fight and see where they move first, then load and attack them again and place trap on that spot and when that lose turn focus all army on them hoping to kill them, or at least decimate them before they poison all your units.
If you post more info about your hero/items/spells and army you have at disposal maybe some better way will be presented to you by players on this forum.