Tanglesap

• WWizards of the Coast2009-10-01
  Official Ruling
  Tanglesap prevents combat damage that would be dealt by all creatures without trample, regardless of whether they’re attacking or blocking.
• WWizards of the Coast2009-10-01
  Official Ruling
  Creatures are checked to see whether they have trample at the time they’d deal combat damage, not at the time Tanglesap resolves.

Rulings via Scryfall