After the Sun God Token took root in Ackster's smelting furnace, it helped subdue the blue sun while siphoning its flames to strengthen itself. But the blue sun hadn't become noticeably weaker. It was just suppressed and dormant.
However, when the flames inherent to Smelting Furnace enveloped the blue sun, it woke right back up and roared with surges of blue fire that tried to fend off the encroaching orange fire.
But Ackster was no longer the same as he had been when the blue sun nestled into his Smelting Furnace. He had grown a lot stronger, and so had his Smelting Furnace. Most importantly, he had Ichor now, which could support Limit Breaker and Smelting Furnace.
Slowly but surely, Ackster's Smelting Furnace ate away at the blue sun, refining its fire into its own. The Sun God Token was relegated to being an idle spectator.
