Every eight hours, you can visit the Shop and select the "Claim" option to obtain 500 free Bolts. These Bolts are totally free and can be used to participate in Duels. That’s 1,500 free Bolts per day.
VIP players receive an additional 500 Bolts every 8 hours, so 1,000 free Bolts total. Even more reason to upgrade to VIP!
The 8-hour timer restarts immediately after you claim your Bolts.