Dromosaur

Oracle Text

Whenever Dromosaur blocks or becomes blocked, it gets +2/-2 until end of turn.

Card Rulings

10/4/2004 If it manages to block or become blocked more than once in a turn, it can get the bonus twice.
10/4/2004 Switching blockers will not re-trigger this since it only triggers on becoming blocked and switching does not unblock and reblock it.