Patch 13.12 overview
Champions you recently played
No change
Other Champions
Passive bonus damage increased. W damage increased. R damage increased.
E recharge rate decreased.
Passive cooldown increased. Q mana cost decreased.
E cooldown increased.
AD growth increased.
Base AD decreased.
W base damage decreased.
Passive damage decreased, activation conditions adjusted.
Base armor decreased. Passive magic damage decreased. E shield value increased.
Base armor decreased, armor growth decreased. Passive empowered attack damage decreased.
Passive life steal increased. R cooldown now decreases with rank.
R damage increased.
Default adaptive stat changed. Q cast time decreased, damage decreased, monster damage adjusted. W Crash Down damage decreased, monster damage adjusted. W Mount Up monster damage adjusted. E damage decreased, monster damage adjusted, damage cap to monsters added.
Base health decreased, health growth increased, base health regeneration decreased. Passive heat limit increased, overheat monster damage cap adjusted, overheat attack speed increased, overheat duration decreased. Q damage adjusted, minion damage decreased, monster damage cap added. W shield adjusted. E heat generation increased. R cooldown increased.
Passive bonus mana increased. E magic damage increased, missile speed increased.
Attack damage growth decreased. W bounce damage increased.
E bonus attack speed decreased. R heal per hit decreased.
Movement speed increased. Passive removed, Q passive added in its place. Q no longer activates Sheen. E critical strike multiplier increased.
Items you recently played
No change
Other items

Ardent Censer
Ardent Censer is providing a lot of damage to marksmen, contributing to ADC death ball and limiting support output diversity. It's the most common enchanter legendary at the moment, which is a space that should be competitive with Redemption, Mikael's, and other options.

Bloodthirster
Bloodthirster is the ultimate greed item for ADCs who can stay safe and deal high damage from the back line. We're upping its cost to be in line with that role as the item is currently overtuned.

Galeforce
Galeforce is a bit overpowered on marksmen and overperforms substantially on both Yasuo and Yone, so the critical strike ratio is being replaced with an AD one. The risk here (and the reason it initially had crit scaling) is poaching by assassins, but an overall reduction in power should keep the item in line for all users across the board. Some players (and one champion) might be pleased to know it takes 444.4444 bonus attack damage to match the damage from the old crit scaling.

Immortal Shieldbow
Players have (for the most part) identified that Shieldbow is not a good first item. Unfortunately, the item just isn't very strong when purchased later, either. This is a relatively light buff, but one that crit users should be able to feel in the mid game.

Imperial Mandate
Imperial Mandate has found itself a new home as a legendary support item and has quickly become one of the default purchases as enchanters' second item. While that's awesome, the item is overpowered and is contributing to League being at one of its burstiest points in recent memory. Overall, these changes are intended as a small nerf, particularly targeting the item's burst output.

Moonstone Renewer
Moonstone is weak on every champion that isn't named Soraka. We're changing the formulas to always give the values that allies of level 14+ were getting in most cases. This typically ends up augmenting the value of heals and shield by ~5% per cast, and giving shields more leniency due to them feeling less disruptive.

Phantom Dancer
Phantom Dancer is underperforming compared to other mid-range crit items so it's just receiving a small buff this patch.

Rapid Firecannon
Rapid Firecannon got substantially stronger when its stat profile moved toward attack damage and away from attack speed. Since the AD on the item naturally scales with critical strike chance, the Energize damage doesn't need to be anywhere near as high as it was before.

Statikk Shiv
Statikk Shiv is meant to be your best source of wave clear without just one-shotting the caster minions. It's still a bit underpowered, so the damage is being ramped up in early game in order to more closely align with minion health bars.
Runes you recently played
No change
Other runes

Overheal
Overheal was meant as an avenue for disenfranchised ADC players to opt into more durability for the games where they needed it. In reality, most players don't typically mess with their rune pages, but pros sure do. Moving Overheal back to a maximum health ratio will open its users up to self-sustaining fighters and tanks while nerfing it for marksmen. Technically, Aphelios gets more shielding levels 1-5, but this is overall a significant nerf otherwise. Meanwhile, it's substantially stronger for high health champions like fighters. Overall, this is still the strongest or second strongest Overheal has ever been.