So basically how she works is:
The elemental link bonus works like the one from troops. So assuming she has 20% heal and 1000 max hp, she normally heals 200 hp; but with the elemental link she would heal 200 HP + 10% of 200 hp so 220 hp in total.
Now for her passive, whenever she gets a status ailment she heals herself 10% max hp. So again assuming she has 1000 max hp, for every ailment received she heals 100 hp. If she has her own elemental link active, she would heal 110 hp.
Now her passive looks meh at first but is actually pretty powerful. Every hit from Bera minion applies two status ailments (poison + immunity to new minions) - which basically means every hit from Bera’s minion heals her 20%. With many moths on map she can heal from critical condition to full hp in but a few minion slashes.