Liandry/morello changes really hurt ryliandry's champions, let's not pretend it was a buff.
Still waiting on compensation changes for ryliandry core champions like Zyra and Rumble. I realize Zyra has a .25 second root buff, which is pathetic considering her E is so slow and Zyra actually roots herself as she casts it. Remove the self-root or make her plants not die the second she brings them up. Rumble on the other hand has been ignored horribly. The buffs several patches ago were pathetic. You don't give microscopic buffs when the champion has a 45% winrate.
Rumble is basically no longer a lane bully since you can't stack heat at very early levels to empower abilities and overheat for punishing any champion that wants to melee you. Those first 1-3 levels were too important to lose because Rumble relied on getting a lead before enemies got MR and could kill him every single time they all in. If you don't want Rumble to be an oppressive lane bully, that's fine, make him a battlemage. Point is, he needs scaling buffs. Make his W and E cooldowns scale from 6 to 6/5.5/5/4.5/4. He'd still be gated heavily by risking self-silence but he would at least not be useless lategame. I really don't care what buffs he gets, but it's undeniable he needs them. He could be a very healthy champion if his focus was teamfighting as a battlemage because it's clear Riot will never allow him to be a successful lane bully again.
Why the Liandry's/Morellonomicon changes were a nerf: Originally, the Liandry's changes on PBE were pretty obviously overpowered, but then the burn damage was halved. The main issue now lies in too many items being core. Zyra relies on pen because her AP ratios are pretty awful. She used to buy Liandry's and Rylai's to have 33 magic pen and the double burn. Now she has to buy Morellonomicon to get the same affect, and the burn damage isn't really changed much. It deals current health, but at half the power, that's a pretty power-neutral change. Zyra even had her mana pool nerfed, making a lost chapter item fairly important, but not quite core. Basically her powerspike went from 2 items, to 3-4 items which is just way too late to actually be relevant. Rumble is in a similar boat but even worse. Like I said, he relied on winning lane and rushing Liandry's. He got nerfed hard before the liandry's changes so now he relies on 2 items and also won't even win lane in most cases.
Point is, stop ignoring Rumble and buff Zyra with QoL changes rather than laughable .25 seconds extra root on an ability that basically kills you with the long-ass cast time. Make Rumble healthy and viable by repurposing him into a battlemage rather than a lane bully.