Question about Charbelcher

[The Grim Reaper]

What happens when you activate Goblin Charbelcher with no lands left in your deck? Does it deal damage equal to the number of cards left in your library? Or no damage at all?

If it's no damage, why do charbelcher builds run 4x landgrant and 1 land...

o.O

Thanks for the help,

Grim

[Toad]

It deals damage equal to the number of cards left in your library. Goblin Charbelcher + Mana Severance is tech.