A fictitious champion idea I have...
I'm trying to decide if this he is going to be from where Renekton and Nasus came from or if he is actually a "distant cousin" of Rammus. (Most likely the former)
Jarkin is a tank that specializes in in-fight sustain and enemy disruption. Jarkin relies on clever positioning in order to combat priority targets with his low-range abilities, while being naturally beefy in combat. He relies on his teammates to deal the majority of the damage unless built with dps in mind, though that would sacrifice a significant portion of his beefiness; he relies on gaining health and sustaing in order to become tanky instead of using natural tankiness abilities otherwise.
Reinforced Armor is Jarkin's method of remaining relatively tanky late game despite champion attempts to gain magic/armor penetration. It is relatively weak early on though so he doesn't become an unkillable lane bully, especially considering the amount of sustain he already has. I made this effect not work against structures because I still want him to feel the full damage penalty for turret diving.
Iron Tail is Jarkin's bread-and-butter enemy lockdown ability. The ability range of Iron Tail is similar to that of related abilities (non-ultimate targeted knockup or knockback abilities). The long cooldown on this ability makes it so Jarkin needs to wait in order to repeatedly lock up his opponent from a fair distance.
This is Jarkin's primary sustain tool. When used against champions, I intentionally delayed the full healing amount so enemy champions can still win short trades. This skill will still provide lots of sustain during extended teamfights. I intentionally gave him a low base health regeneration stat in the early game in order to make Jarkin more reliant on this ability for lane/jungling sustain.
This is Jarkin's gap-closer ability, providing more crowd control. This ability is designed to help him catch up to opponets. However, his large body size combined with the meager range on this ability makes it so that this ability cannot make him go through the thicker walls on Summoner's Rift.
For this ability, I want to make it similar to the ultimate abilities of Nasus and Renekton. This ability offers more utility than the other abilities though because of the Armor/MR shred.