You take no Battle Damage from battles involving this card. When this attacking card is destroyed by battle and sent to the Graveyard, Special Summon 2 "Rockstone Tokens" (Rock-Type/EARTH/Level 1/ATK 0/DEF 0). These Tokens cannot be Tributed for a Tribute Summon.
Works well on two fronts:
1. You take no battle damage from battle damage with this card. Your opponent springs a monster on you while its in attack position your still safe.
2. If your opponent springs a monster while its your turn but you cant overcome it, ram this monster against theirs and you now have two defenders.