I am not saying make it like that I am saying it wouldn't be anywhere near as crazy as theirs is.
Garen has a ton of passive consistent healing.
Mundo gets a ton of consistent passive healing on top of his Ultis burst heal.
Rek'Sai has to have a full rage bar to get maybe like 15 percent of half of what they heal.
Garen and Mundo can heal a full health bar in seconds.
Rek'sai can heal less than half of what they heal in 30 seconds if she stacks her rage bar consistently. Like i said though im not asking to have the healing put anywhere near their level. Just maybe make it like 2-3 percent or something lower per tick if she does it with full fury.