As with any champion design, the most important thing about them is their "Power Fantasy".
The Power Fantasy defines everything there is to know about a champion from both lore and gameplay perspective. For example Orianna is a dancer by nature, performing a constant tango between her and her ball. Draven is a showoff who loves to stand out and perform for the crowd. Sion is a gargantuan undead warlord who shakes the very ground under his assault. Jinx is a mayhem sowing excitement lover who blows up things for fun before speeding away chasing the next thrill. Etc. And every champion has one.
When a champion really makes you go "Wow..." and takes your breath away, it's pretty much always because they have a power fantasy which matches what you personally like.
When it comes to Rammus however it's difficult to really pinpoint an exact Power Fantasy for him. What does he do which could really be put down as THE reason to play him.
He taunts people... He rolls around really fast... He's exceptionally tanky... He makes enemies kill themselves when they attack him... He stacks Armor... He makes Earthquakes happen... He says OK and grunts a lot...
Personally, I would put down his Power Fantasy, his character defining attribute, as being that roll of his. He can curl into a ball to move at incredible speeds, however becomes less tanky from doing so (incapable of getting the Armor and MR from his Defense Curl). Other things improve and flesh out his playstyle, his taunt is a big part of his gameplay but it doesn't define the character quite like his Powerball does.
And that's the real point behind this mock fan-rework. (And as the "Pt. 1" in the title implies there is another armor stacker rework coming soon after)
There is in particular one play which all Rammus players like to do which involves charging in with Powerball and then flashing directly onto the enemy, ether catching them off guard or using it to bypass minion waves. Which I wanted to make easier by adding a new skill dedicated entirely to that purpose.
Rammus gains 10% increased damage from all of his attacks and abilities for every 100 armor which he has.
Enemies Taunted by Rammus take 5% increased damage from all other sources for every 100 armor Rammus has.
Active: Rammus curls up into a ball, instantly shredding 20% of his current armor, over the next 3 seconds this armor shred is increased to 50%. While Powerball is active Rammus gains flat movement speed equal to how much armor he has lost and an additional 20%.
Colliding with an enemy will knock up all enemies in the area for a brief time, dealing damage to them and slowing them by 50% for 2 seconds.
Rammus ends his powerball when he ether reactivates the skill, the ability times out after 7 seconds, Rammus casts Rockfall or upon colliding with an enemy. Any lost armor is returned gradually over the next 5 seconds.
Powerball halves Rammus' armor however grants him a huge speedbuff based on how much armor he has. At 100 armor he gains up to 50 movement speed, at 200 armor he will gain up to 100 and at 300 armor he will gain up to 150.
Powerball's armor shred does NOT reduce the damage Rammus deals using his passive.
The 20% extra applies to all flat MS Rammus has including the MS from the shred.
At 100 armor Powerball deals 110/137.5/165/192.5/220(+55% AP)
At 200 armor Powerball deals 120/150/180/210/240(+60% AP)
At 300 armor Powerball deals 130/162/195/227.5/260(+65% AP)
Defensive Ball Curl
COST: 40 Mana
Active: When Rammus is not in Powerball form W is Defensive Ball Curl. Rammus instantly cleanses all non-lingering Armor and MR debuffs and does a spike of magic damage in an AoE around him.
Magic Damage: 50 / 75 / 100 / 125 / 150 (+50% AP)
After the spell completes Rammus gains a buff for 6 seconds. When Rammus comes under attack by an auto attack Rammus deals magic damage to the attacker.
Return Magic Damage: 20 / 30 / 40 / 50 60
COST: 40 Mana
Active: While Rammus is in Powerball form W becomes Rockfall and becomes available to cast when Powerball is fully charged (shares the same cooldown with Defensive Ball Curl). Rammus jumps a fixed distance the way he is facing dealing Powerball's full effects to enemies he lands on, this allows Rammus to jump over obsicles while in Powerball form. Rockfall will cancel Powerball and put it on full cooldown even if Rammus doesn't hit a target.
Upon landing Rammus also gains the same buff for 6 seconds which returns damage to attackers.
With W, Rammus can choose whether to leap over minions using Rockfall however he will suffer the penalty from his Powerball for the full duration and be really squishy for a few seconds. OR he can choose to Powerball directly up to the enemy and then use Defensive Ball Curl in order to instantly become tanky again and do more damage too.
Rockfall requires careful aim in order to land on a moving target, because it travels a fixed distance it is easily jukable by walking towards Rammus when he uses it.