The three laws

First Law — At the beginning of your upkeep, if
you control a creature, prevent all damage that
would be dealt to that creature this turn.
Second Law — Whenever a creature you control
deals damage to another creature or player, if the
damage is greater than that creature’s power, exile
the attacking creature at the end of combat.
Third Law — You can’t activate abilities of
creatures you control that would result in them sacrificing themselves or another creature.
.