Promethean Colossus

Trample
When Promethean Colossus enters the
battlefield, destroy all nonbasic lands you control.
For each land destroyed this way, add {r}{r}. Until
end of turn, you don't lose this mana as steps
and phases end.
If you would lose unspent mana, that mana
becomes {r} instead. Promethean Colossus deals
that much damage to you.