Not hard to find

Search in your library for a creature card with converted mana cost 6 or more, then put it in yor battlefield without paying it's mana cost. Shuffle
your library.
Target creature with converted mana cost 5 or
less gets tapped and does not untap until your
next turn, it also cannot activate any of it's
abilities.
If you summon a creature with first strike using
this card, destroy target tapped creature