Underrealm Lichs' Cast. Cost

Whenever you cast Underrealm Lich from
your command zone, put two cast counters
on Underrealm Lichs' Casting Cost. As an additional cost to cast Underrealm Lich,
pay {x}, where {x} ist the number of cast counters on Underrealm Lichs' Casting
Cost.
Should be legendary - no doubt.