"Incandescence, Collapse orbs, Fall Back!" Süne ordered. And a few things happened at once.

While Süne misjudged Tibearius' landing for aiming his blizzard, fortunately for him, he did so by less than the radius of the blizzard. As Tibearius was staying stationary and launching attacks from 5 feet away from where Süne had aimed the 8 foot radius blizzard, it would be caught in the blizzard and start taking some very minor damage, given its resistance. 

The Echo of Rend would stop short before hitting Sakura-re. She had been moving directly to Süne's right, dodging to avoid Tibearius' landing which Süne assumed would be directly on top of her, and feared might have a vast radius, and also the blizzard Süne had been intending to cast there. Süne's blizzard was 8 feet in radius, and Sakura-re aimed to get at least a foot clear of that, which given Tibearius had stopped 5 feet of her initial location, gave the current distance between them to be slightly more than the 10 foot range of Echo of Rend. And this was assuming she stood still during the travel time, which she did not.

Meanwhile Sakura-re activated Incandesence, and began moving her Orbs at Tibearius. Sakura-re only had to move her LoI that was closest to her a single foot before it would start effecting Tibearius with its damage, which hopefully be easy to do with a blizzard currently sitting on top of Tibearius, and it would immediately interrupt channeled abilities, given it's 6 foot range for that. From behind Tibearius, Sakura-re recalled her other LoI to catch Tibearius if he backed away from the light moving towards him from within the blizzard.

Süne fired off a Frozen Sphere at Tibearius, cheating a little bit to the side Sakura-re was facing, but still aiming for a direct contact. With the current distance between them, the attack would land in just under a second, with a blizzard obscuring the launch from Tibearius' perspective. He continued charging whatever Searsinging spell he was charging.

And lastly for the group of things that happened simultaneously, Sakura-re started moving toward's Süne's edge of the arena wall instead of of the edge to Süne's right, so that if Tibearius did happen to want to give chase, he would either have a longer path through the blizzard, or he'd need to skirt its edge for longer. Süne didn't want Sakura to lose one of her potential dodging directions in going to the right, so currently she stayed at 6 feet away from that border of the arena.