Nether Star shards will replace skull drop.
8 shards + 1 nether star can be crafted in two Nether Stars (the original one and the new one)
Chance for dropping:
+2% for each wither killed up to 50% to drop a shard (killed_wither_times / 2 + 1, up to 9 times possible shards drop). That means that at 10 withers killed the wither will have 50% to drop a shard, another 50% chance to drop a second one, another 50% to drop a third one, etc. up to 6 shards.

Closed with 761855e