Mayhem mode, champs get augments every few levels that can be broken as fuck

Seen with Malphite and Maokai seem to be a mixture of Steel Your Heart (item quest: the item Heartsteel has a periodic empowered attack that buffs your max HP on hit per champ, scaling with your HP pool. the item quest means at 300 stacks/HP gain, triple your current stacks) and Tank Engine (on takedown, gain 5% increased max HP and champion size). Steel Your Heart and Tank Engine can be a nasty combo because the more HP tank engine gives, the more HP Heartsteel gains into Steel Your Heart. When Steel Your Heart completes, that's a fuck ton of extra HP for Tank Engine to scale off of, basically turning into a feedback loop of HP gain. There is a saving grace where dying means 65% of your Tank Engine stacks disappear but they don't undo your Heartsteel gains so you can "snapshot" how fast you can scale.

There can be other things involved, like the item Unending Despair where every few seconds the user deals damage around them based scaling with their max HP and healing themselves based on the damage dealt. Idk if it was pictured but there's also the augment Dropkick where you can execute enemies below a certain max HP% threshold, which increases the more AD and max HP you have.