Very nice concept! I really like the idea of a magical wielding knight since we don't really have any (no, Mord doesn't count). This could be the niche top laner that team comps could pick when their mid and jungler go AD. So far we really only have Morde, Kayle, Rumble, Ryze, and some AP flex picks like Sylas and sometimes Singed. I for one would love to see more AP in the toplane and I think you're onto something. Though, it does beg the question of what region he will belong to. We typically think of knights and military warriors coming from Demacia, but as we know Demacia doesn't like magic users cough Sylas cough. So that small discrepancy would have to looked at lol.
I'll talk about each portion of the kit separately! We can start off with the passive!
Runic Sword (Passive): After casting an ability, gain increased movement speed moving directly away or towards the nearest enemy champion and bonus magic damage equal to a portion of your ability power on your next attack.
Thematically, having a weapon being a knight's passive is very meta (which is good for clarity of the theme we try to portray). The added effect of dealing bonus damage after spellcast also works to further clarify the role (which I think is fighter/bruiser. Please correct me if I'm wrong) but it really works to convey the idea that this character isn't JUST another AP caster, he's actually an AP fighter, which is a really cool idea!) The one thing that I would like to see changed would be the portion of the passive that gives you movement speed away from your target. That's not thematic, since knights are loyal and noble- never backing off from a fight. Just my two cents. Let's see how some numbers would help cleanup this passive!
- Runic Sword (Passive): After casting an ability, gain 10 - 40 increased movement speed (based on level) moving towards an enemy champion. Additionally, gain 10-80% (based on level) of your bonus AP as bonus magic damage on your next basic attack.
This passive is slightly stronger than Vayne's passive which caps at 30 movement speed. Since Runin is melee he'll need slightly more movement speed to get into position, but not too much where he becomes overwhelming since he already has a dash. Onto the rest of the kit!
Magic Bolt (Q): Throw a magic bolt at the target unit, dealing magic damage. If the bolt kills the target, it explodes and deals the same damage to nearby enemies.
I hate to break it to you, but Riot really wants to move away from point-click abilities and as it's written, this ability looks like it's point-click lol. The good news is that Runin uses a sword... and swords can slash, pierce, swing etc. which gives us a lot of room to explore! It will ultimately be up to you in what direction you would like this ability to go. Personally, I think a slashing action with a cone indicator would really work for the theme of a sword user, but so could a jab or a spin (think Garen). For this sake I'll use a jab as an example. Using a jab opens up a window of opportunity for an auto attack reset, which are GREAT for fighters. The more auto attacks you can weave in between downtime, the higher your DPS. Now we have to work in the second half of the ability which is to deal damage to everyone around the target when the unit is killed. I see no issue with this. Think of it as a mini Tiamat that only triggers when you kill a unit. Cool! Let's add some numbers to round out the ability!
- Magic Slash? (Q): Runin's next basic attack deals 60/70/80/90/100 (+40/60/80/100/120% bonus AP) magic damage. If the attack kills a target, it explodes and deals the same damage to nearby enemies.
COST: 40 / 45 / 50 / 55 / 60 MANA
COOLDOWN: 5
I know what you're thinking, "that scales really well into the late game, holy cow!" Well... yeah... most fighters do too lol even Morde! The simple fact that it's a bread-and-butter attack modifier without a slow, stun, snare, true damage, etc means that we can justify loading it up slightly. A simpler ability format will also allow for users to pick up this champion much faster than other. Because, let's be honest, Riot has been releasing some COMPLICATED champions... can we just have a basic champion? Lol.
Counterattack (W): For half a second, prepare to block any ability or attack from the target direction. If successful, bash the area in front of you with your shield, dealing magic damage.
This is literally Fiora's Reposte without a stun... which isn't that great when compared side by side. We need Runin to have an identity, and giving him Fiora's W as his W isn't going to cut it. Let's see what we can come up with! I suggest we do something to further highlight either his identity as a rune user (aka magical stuff) or as a knight (aka fighting stuff). For thematic sake, I think we should use some magic? The original ability you thought up of was basically a way to mitigate damage and you also mention that Runin has a shield, so how about we give him some damage reduction?
- Shields Up! (W): Runin raises his shield, gaining 2/3/4/5/6% damage reduction for 4 seconds. After the duration, Runin bashes forward, dealing 10/20/30/40/50 (+80% of the mitigated damage) to enemies in front of him.
TARGET RANGE: 400
COST: 40 / 55 / 70 / 85 / 100 MANA
COOLDOWN: 12
Another simple ability lol. I'm starting to think this champion is too good to be true. The good news is that if Riot ever decided to go back to their roots (simple kits) they might look at this post and have nostalgic flashbacks :P
Magical Slashes (E): Dash 600 units in the target direction, slashing three times. Each slash deals magic damage in a wide cone in front of you as you move.
There isn't much to this ability (which is a trend I've noticed lol and not in a bad way!) It's a simple dash effect with damage attached to it. We can easily compare this to Ezreal's Arcane Shift, Fiora's Lunge, Caitlyn's 90 caliber net, and Corki's Valkyrie. My one issue with this ability is the second portion, the 3 slashes. As much as I would love to see an ability like this in the game, I just don't think it fits Runin's identity as a knight. Tipically, knights carry around short, long, and some even bastard swords which are all kinda hard to maneuver (I've held many in my life time lol) Dashing forward is already a feat in and of itself, but now we have to slash not once, not twice, but THREE TIMES lol. My comment is based off reality, and I know League is a fantasy game, but I would urge a small change. Simple in fact. Let's just slash once!
- Magical Slash (E): Runin dashes 600 units in the target direction, dealing 40/60/80/100/120 (+40% bonus AP) magical damage to anyone in his path. Upon reaching the end, Runin slashes once, dealing 80/100/120/140/160 (+50% bonus AP) true damage.
TARGET RANGE: 600
COST: 50 / 55 / 60 / 65 / 70 MANA
COOLDOWN: 8
It's a tough call when giving champions a form of true damage, but given that this doesn't do %health as true damage I feel like this change is justified. I believe Runin would be used in the top lane and some form of dealing with tanks is always appreciated. Runin, thus far, has been dealing magical damage for the most part so switching it up and giving him some true damage makes it so that he isn't completely countered by MR stacking tanks like Mundo or... basically any tank lol.
Grand Visionary (R): Become visible to all enemies as you glow and charge up your most powerful attack. After 3 seconds of charging, deal 40/50/60% remaining health magic damage to all enemies with a lane-wide magical beam that travels quickly to the end of the map.
Umm... Uhh... Global abilities like this one are usually just carry abilities (Ashe, Ezreal, Draven, Senna all of which are ADC's) I don't think the world is ready for a fighter to have a global ability. Pantheon and Galio are both examples of fighters that have semiglobal ultimates, so let's explore that avenue when trying to see what we can do with Runin. The fact that it's no longer global means we can beef it up a bit! For starters, we should totally give this ability base damage, and we can change the "remaining health" to "missing health" lol, just to clarify that the ability functions as an execute. We'll have to decrease its range though, but it shouldn't be that much of an issue since champions like Twisted Fate and Pantheon are notorious for their global presence, without having a global ability. Let's see what this ability could look like with some number adjustments!
- Grand Visionary (R): After 2 seconds of channeling, Runin creates a long range blast of magical energy from smashing his sword into his shield, dealing 150/200/250 (+70% bonus AP, +20/30/40% of the target's missing health) magic damage to all enemies struck.
TARGET RANGE: 4000 / 4500 / 5000
COST: 100 MANA
COOLDOWN: 220 / 200 / 180
As you can see, I lowered the channel time to something a bit more reasonable. 3 seconds was much too long, and could easily be canceled. 2 seconds also seems too long, but it could serve as a finisher for fleeing opponents. While I do like the execute potential of this ability, we can't have anything higher than 50% since that would be very hard to balance. Having it scale as the game progresses allows Runin to have a fighting change against tanks as they scale into the late game and begin to stack health with the added advantage of being able to hit the back line carries if you position correctly.
All and all these are just some suggestions and by no means do I wish to step on Shirotaki... wait a minute... didn't I already review a champion from you?! :O
EDIT: I had to put in the mana costs, ranges, and cooldowns. Lol how unprofessional of me.