[Champion Concept] Electromagnetism control mage -- Severa, the Headmistress
THEME: Middle-aged Headmistress of a prestigious Piltovian university. Dresses business casual always. Likes Cait and Camille, dislikes everyone else. Wears a monocle.
ROLE:
Mid lane mage with aspects similar to 
. The side of the map Severa's on effects her abilities. Enjoys better-than-average mobility for her class and strong soft CC, but has highly telegraphed damage and can buff her enemies if her abilities are used incorrectly. Weak in inhibitor sieges since they only take place on one side of the map; very strong in Baron/Dragon fights due to AOE and adaptability from being able to easily access different Polarities.
Passive: - Static
- Trinket wards within 1600 range have their vision radius increased.
- Abilities use a Polarity mechanic. Blue Pole corresponds to blue side of Summoner's Rift, Red Pole to red side.
Q: - Point Charge Afflicts ground targeted area with Polarity for 10 seconds, depending on the side of the map the selected area is on. Enemy champions can dissipate Polarity by standing on the area for 5 consecutive seconds, but they become Conductive while doing so. Additionally, an enemy inside the area will get zapped every second, prioritizing minions (think Swain Q). Conductive enemy champions take 30% increased magic damage.
Cooldown 10/9/8/7/6 seconds
Cost 50 mana
Range 1500 units
Effect radius 400 units
Damage 50/60/70/80/90 + 40% AP magic damage
W: - Summon Electromagnet Calls up a block of charged metal and from the ground, with the Polarity depending on the side of the map. Detects the closest Polarized area or other Electromagnet, and moves towards if the Polarity is different, and away if the Polarity is the same. Moving Electromagnets deal damage to all enemies hit. If they hit her, she jumps on and rides it for the remaining duration. Electromagnets cannot go through walls, and cannot change direction mid-flight Blocks last for one minute, max 1/2/3/4 at levels 1/6/11/16.
Cooldown 10 seconds
Cost 100 mana
Summon range 700 units
Projectile speed 1500 units per second (medium-speed projectile)
Collision size 200x200 unit square
** Collision Damage** 100/150/200/250/300 + 90% AP magic damage
E: - B-Field Vector cast square area in the specified direction. Conductive enemies moving in the cross-product negative direction (i.e. running in a direction clockwise to the direction the ability was cast) are grounded, slowed, and suffer magic damage every half-second. Conductive enemies moving in the cross-product positive direction (i.e. running in a direction counter-clockwise to the direction the ability was cast) are immune to slows. The severity of the slow and magic damage depend on the specific angle of movement, zero if moving parallel to the vector field and maximized if moving perpendicular to the vector field. Electromagnets inside the field have their momentum halted if moving in the cross-product negative direction, and their Polarity swapped if moving in the cross-product positive direction.
Cooldown 15 seconds
Cost 70 mana
Cast range 800 units
Effect size 500x500 unit square
Maximum slow 50/55/60/65/70% + (10 per 150 AP)%
Maximum magic damage per half-second 20/30/40/50/60 + 35% AP
R: - Potential Difference Spawns an expanding magnetic pulse around Severa with Polarity depending on side of the map, disabling enemy wards hit by it. If the ring touches any Electromagnets, a new ring is spawned with the Polarity of the Electromagnet spawning it. Enemies struck by a single pulse take damage, tripled if hit by two or more pulses of opposing Polarity.
Cooldown 120/100/80 seconds
Cost 100 mana
Maximum effect radius 900 units
Damage 75/150/225 + 60% AP
PLAYSTYLE Severa revolves around her W, as it is her most reliable way of damaging opponents outside of her ult, in addition to being the keystone of her entire kit. Electromagnets are somewhat similar to Orianna's ball, but controlling them is done with a pushing/attracting force, rather than directly with Orianna Q. Since they only interract with the closest Polarized thing, there's no wonky vector addition going on (sad, but I have a feeling there's a reason we haven't seen any skillshots which can change trajectory midflight in an unpredictable manner). I also feel like the kit is complicated enough as it is. Feel free to convince me I'm wrong, however. More on these in a bit.
E is the hardest ability to explain without visuals. Basically, think righthand rule - if the thumb of your right hand is the direction the ability was cast in and the index finger is the direction of movement, the middle finger is either the crushing, downward force which grounds and causes damage/stops moving Electromagnets, or the upward, lifting force which causes slow immunity and swaps Electromagnet Polarity. This ability has a ton of counterplay - first of all, they need to be Conductive, meaning inside the Q area, and even then, the enemy is in complete control over whether or not they get CC'd and take damage, or get slow immunity. Thus, the direction it's cast in is really important -
Eample: Cast SouthEast if on blue side means your opponent has a perfect slow immunity for running NorthEast up the lane back to mid turret. Casting it NorthWest in the same situation means your opponent has to slug through a heavy slow, take max magic damage, and be grounded to run back to turret... unless they run SouthWest towards your turret to escape the B-Field and loop back around.
Her W can be used in so many different ways. Because her Q, E, and R all have interactions with Electromagnets, she has many tools at her disposal for pushing them around and using them for damage or for escaping, and can even do both at the same time with the correct setup. Here's an example:
In lane, place a Point Charge around your melee minions, zapping a few enemy melee's, and summon an Electromagnet just in front of it. Being the same Polarity as the charged area, it will shoot away from it, damaging minions and potentially your lane opponent. Then, throw another Point Charge on your opponent's side of the lane. Since the Polarity is the opposite of the Electromagnet which just hit your opponent, it will rush towards it, potentially hitting them again... or you can cast B-Field on the Electromagnet, either stopping it for use as a anchor point for your next Electromagnet, or switching it's Polarity and repelling it from the last Point Charge.
Riding Electromagnets is done by standing in front of them while they're inert, and then throwing a Point Charge, causing it to rush towards you and pick you up. You can stop momentum prematurely with a correctly-oriented self-cast B-Field, then specify a new direction with a new Electromagnet/Point Charge.
So basically, she can indirectly control a few of these buffed Q's at once. She uses precise configurations of opposing-Polarity Electromagnets, however, to significantly increase the damage of her ult - the bonus damage only occurs if someone is hit by the expanding rings of opposite Polarity at the same time. No extra damage is taken if someone is hit by two of the same - colored rings, or one ring and then another a half-second later.
As per usual for control mages, she's squishy and pretty bad at dueling mobile champions who can dodge her W's, but is an excellent teamfighter and provides unique utility with the ward enable/disable. That's not to say that she's like 
and auto-loses to assassins/
, however - clever use of B-Field combined with a hurtling Electromagnet can really throw a wrench in their plots, but it's not easy.