Ruins of Rats

You may look at the top card of your library at
any time.
You may play lands and cast spells from the top
of your library If you cast a spell this way, pay
life equal to its mana value rather than pay its
mana cost.
{t}, Sacrifice 10 nonland permanents: Each
opponent loses 10 life.
"The Rats will prevail in the end.
In your demise we rise."