Rammus received a non-scheduled balance update during patch 13.1. The champion appeared too weak at the start of the ranked season in League of Legends. According to data miner Spideraxe, Rammus got several buffs to his base stats and one ability.
The game developer Phroxzon explained the buff with a 9% winrate drop, which happened after the latest nerf to the champion's abilities. He also mentioned fixing a bug related to Seraph's shield. It was activated after taking 30% HP as incoming damage instead of at 30% health.
Rammus was nerfed in patch 13.1, which came out on January 10. The next update will arrive on January 25. It will add the new Ahri with updated visuals and possible balance changes.