Hei Bai, Spirit of Balance

Hei Bai's last ability puts all counters that were on Hei Bai onto the target creature, not just his +1/+1 counters.

If Hei Bai has -1/-1 counters on him when he leaves the battlefield, that ability will include those as well. This may result in the recipient of the counters dying.

If enough -1/-1 counters are put on Hei Bai at the same time to make his toughness 0 or less, his last ability will see all of the +1/+1 counters he had when he left the battlefield as well as the -1/-1 counters he had, and an equal number of each of those types of counters (plus any other applicable counters) will be put onto the target creature.