(Tree Catacombs isn't a spell.)

At the beginning of your end step, if you didn't cast any spells this turn, Tree Catacombs deals 1 damage to you.

Tree Catacombs is indestructible. (Destroy effects and lethal damage don't destroy it.)

: Add  or to your mana pool.

: Add  to your mana pool. Put Tree Catacombs on top of your library.