Kai, Spirit of the Dragon

At the beginning of your end step, target opponent loses 1 life and you gain 1 life for each other tapped creature you control.
Whenever a dragon attacks, you may tap Kai, Spirit of the Dragon, if you do, it gains +3/+3 and deathtouch until the end of turn.
" An elder dragon trapped in trapped in the body of a human, all shall fear him"