how does yuumi's heal work

Yuumi heals herself, with the base amount increased by 0% − 130% (based on target's missing health) and the scaling amount increased by 0% − 300% (based on target's missing health), and gains 25% (+ 10% per 100 AP) bonus movement speed decaying over 2 seconds.

minimum heal: 30 / 40 / 50 / 60 / 70 (+ 10% AP) maximum heal: 69 / 92 / 115 / 138 / 161 (+ 40% AP)

this is according to the wiki btw

edit: the base heal increases by 13% for every 8% of missing health and the ratio increases by 30% for every 8% of missing health, according to the wiki