An idea for garen (numbers subject to change)

Rework his passive to have a shorter cooldown (I'm thinking 5 seconds at level 1, 4 seconds at level 11, 3 seconds at level 16) and grant increased regeneration based on missing HP.

level 1 perseverance = after 4 seconds, gain increased regeneration based off of missing hp (+5% base HP regen for every 1% missing HP for a maximum of 495% increased regen at 1% HP).

Level 2 perseverance = after 3 seconds, gain increased regeneration based off of missing hp (7.5% base HP regen for every 1% missing HP for a maximum of 742.5% increased regen at 1%HP)

Level 3 perseverance = after 2 seconds, gain increased regeneration based off of missing hp (+15% base HP regen for every 1% missing HP for a maximum of 1485% increased base HP regen at 1% HP).

If we look Garen's base regen at level 1 it's 7.8 regen (presumably over 5 seconds, I'm looking at wiki). so at max efficiency this thing will have garen's regen at 38.61 regen.

At level 11 his base regen is 12.2 regen. This translates to 90.585 regen at max efficiency.

At level 16 his base regen is 15.1. This translates to 224.235 regen at max efficiency.

These are unadulterated (no spirit visage).

NEW EFFECT = Garen loses perseverance's effects after 3/3.5/4 seconds upon taking damage instead of immediately.

This new effect is because the new perseverance is arguably not as effective as the new one due to the fact that its missing HP based instead of flat regen boosts, so it loses effectiveness the more HP garen gets. This allows garen to go for short Q trades in lane without feeling too shitty about it and rewards the enemy for prolonging fights. Late game this thing scales relatively well since the effects last 4 seconds but his cd is only 2 seconds. Once again though, he will be punished in extended trades that can keep his passive off even when the effects end after 4 seconds.

Although the passive itself seems rather weak, it scales rather well when coupled with items that increase base regen like zzrot and scales rather well with spirit visage.

Take some power out of his W and put it in either his Q, E, or ult so that his damage can be in line with other juggernauts. This passive will make up somewhat for a slightly weaker W with the way it works (persisting for a short while even after taking damage). Garen would be able to feel like an actual juggernaut instead of a CC-less tank late game.