Thought Lash
Enchantment
Cumulative upkeep—Exile the top card of your library. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When a player doesn't pay this enchantment's cumulative upkeep, that player exiles all cards from their library.
Exile the top card of your library: Prevent the next 1 damage that would be dealt to you this turn.
Mark Tedin
Masters Edition II (ME2)
• #70Rulings
If your library has no cards in it, you can’t activate the last ability.
(wotc • 2008-10-01)
If you don’t pay Thought Lash’s cumulative upkeep, you’ll sacrifice Thought Lash as normal, then, when its triggered ability resolves, you’ll exile all cards in your library.
(wotc • 2004-10-04)
Rulings
If your library has no cards in it, you can’t activate the last ability.
(wotc • 2008-10-01)
If you don’t pay Thought Lash’s cumulative upkeep, you’ll sacrifice Thought Lash as normal, then, when its triggered ability resolves, you’ll exile all cards in your library.
(wotc • 2004-10-04)