Irzonk, Goblin King

Goblins get +1/+0 and have mountainwalk.
Goblin spells you cast cost {x} less to cast
where {x} is equal to the card's colorless
mana cost.
To be king, Irzonk did in Numsgil, who did in
Blog, who did in Unkful, who did in Viddle,
who did in Loll...