Ring of Lightning Strikes

Your unarmed strikes deal a bonus 1d4 lightning
damage, and when you deal damage with an
unarmed strike, the ring gains 1 charge (max 20).
As a bonus action, you may spend 20 charges to
gain the following effects until the beginning of
your next turn:
• Your unarmed strikes gain Knockback 20 ft
and Area Of Effect 10 ft
• The rings damage is boosted to 1d8