Sacarz, Skeletal Hoarder

At the beginning of your upkeep, create a
1/1 skeleton thief creature token with: "When this creature deals combat damage to a player, create a
treasure token.
{5}{b}{r}: Sacrifice X treasure tokens and all skeleton tokens created with Sacarz; exile the top X cards
from your opponents library. You play lands and
cast spells from among them this way without
paying their mana costs. Only activate this
ability once per turn.