Greater Krayt Dragon

Trample
{x}{x}{r}{g}{w}: Monstrosity X (If this creature isn’t already Monstrous, put X +1/+1 counters on it and it becomes Monstrous)

Other Monstrosity abilities you activate cost X less to activate, where X is how Monstrous this creature is. This effect can only reduce the amount of {c} mana spent to activate those abilities.