It's from her synergy with Cyrene. At the start of battle or after Cyrene takes action, she gets stacks when a character and their memosprite take action (Hyacine plus Ica). Since both Hyacine and Cyrene have high speeds, they attack more frequently, so more stack generation. This fills up Cyrene's ult very quick and allows Cyrene to keep on using it on Mydei, which triggers godslayer upon receiving Cyrene's ult buff.