Steak

The legendary steak is a one time use item you can unlock at level 81. you only have a 0.0000098% chance of getting this item as it is normally reserved for the developers.

The steak will drain the stamina from 20 random online server members and give it to you, as well as giving all of your troops a 300% attack boost for 1 march.

You could also opt to sell this steak for 30,000 gems if you so please.