Blast Furnace Juggernaut enters the battlefield with five inertia counters on it.
Trample
Blast Furnace Juggernaut can't attack, unless you pay

, where X is equal to the number of inertia counters on Blast Furnace Juggernaut.
When Blast Furnace Juggernaut attacks, remove two inertia counters from it.
For Challenge # 153. I kind of wanted to add an inertia counter at the end of each turn... but I guess this card is wordy enough.