She's somewhat similar to Syndra in that her kit revolves around interaction with static objects left on the battlefield. Syndra's kit is mainly built around manipulating her Spheres in some way (She Creates them, moves them specifically, pushes them, and throws them at people). Sheraze's kit by contrast involves abilities which either interact with the flames in some way, or cannot be cast without them. She is very much a Zone Control champion and is very weak without a Shadowflame to cast with, to the point where she can only activate one ability without one, and that for very minor damage.
Generally, she is immobile and requires careful management of Shadowflame positioning in order to deal damage. Her teamfight presence is quite powerful: Q provides an AoE cc, W provides another AoE cc and high damage, E has a low cooldown and can be used to repeatedly deal damage, and her ultimate, Nether Gate, is an incredibly powerful disruption and area denial ability, similar to Veigar's Event Horizion made into an ultimate.
Shadowflames: It's impossible to describe Sheraze's kit without first looking at the Shadowflame: they are untargetable objects which exist on the field for a fairly long duration after they are created. They deal very minor damage to things near them mainly because it wouldn't make sense for an enemy to stand on a flame and not be taking damage (this damage is low enough to be basically just cosmetic, and doesn't apply any kind of effect). All of her abilities interact with them in some way, and W E R cannot be activated without them. Flames do not give vision, nor do they interact with anything else in any way aside from their passive damage.
"Passive - Shadowflame Creation:" Sheraze has two 'passives', one of which is actually an active ability, and both of which add flames to the field. The reason I chose to give her an extra active, was the fact that I didn't want to have an ability like Syndra's Q (aoe damage and create an object for other abilities to interact with) and yet I needed a way to create Shadowflames in a reliable way.
-The passive portion occasionally creates a shadowflame when you kill a unit and just serves as an interesting way to keep flames on the field.
-The active portion does nothing but create a flame at a target location, with a delay so that the flame can't be interacted with instantly. The range becomes very long as Sheraza levels up, because I wanted her to generally have flames where needed and be limited by her spell ranges.
Q - Void Burst: Q has two uses. When targeted on a Shadowflame, it destroys that Shadowflame to deal AoE damage and pull targets into it. Q also serves as a creation mechanism for Shadowflames: champions hit will create a shadowflame under them before they are pulled. The reason it destroys the flame it hit, is so that there is some risk to using it to clear minion waves.
Secondly, Q can be ground-targeted to deal very minor AoE damage in a tiny radius, and spawn a shadowflame. Given it's cooldown it should generally be bad to use it in this way, but it can allow for emergency flame creation when needed.
W - Dark Lightning: This is definitely her most unique ability. It must be cast twice to activate, with each cast selecting one shadowflame out of all the flames on the map. Neither the fact that W has been activated, nor which flames were selected, is visible to enemy champions, and the two flames must be selected within 5 seconds of one another or the ability is canceled but does not go on cooldown. Once two flames have been selected, a line indicator is drawn between them in a similar manner to a Lux ult, and after a half second delay a large amount of damage is dealt to all enemies in the line. The area of effect is significantly smaller than a Lux ult, and should generally be somewhat hard to hit. Enemies hit are subject to a massive slow for one second, which then decays to zero over the remaining slow duration. The idea of this is to lock targets hit in place allowing other abilities to be used.
Dark Lightning is Sheraze's most damaging ability, though it costs a significant amount of mana. Both flames can be selected globally, though obviously the range of the ability is limited by the existence of shadowflames where you want them, since landing Dark Lightning would rely very heavily on an enemy being directly between two flames.
E - Shadow Rage: Ideally, I wanted Sheraze to not have any way of moving her flames; flames would just stay at the location they were created at until they vanished. However, given the fact that two of her abilities require very precise placement of shadowflames, she needed a way to get them in position or would be utterly useless against any kind of mobile enemy. Shadow Rage allows her to move flames quickly. It is targeted in the same way that Viktor's Death Ray is targeted, with one interesting twist: instead of being cast from Sheraze, it is cast from any shadowflame within 850 units of her. Mechanically, you would click on or near a flame, then drag the cursor to a target point and let go, at which point the flame would move from it's current location to the targeted one, damaging everything it hits. The cooldown of Shadow Rage is also a property of each Shadow Flame: in a similar way to Yasuo's dash, Shadow Rage has a very low cooldown but can only affect a specific flame every so often. The cooldown would be displayed as a bar over the flame, similar to the charge of Heimerdinger's turrets. Since Shadow Rage is primarily about moving flames, it deals low damage and hitting the same target multiple times in a row does even less damage, so stacking flames on one target quickly won't burst them down.
The mana cost on Shadow Rage is quite strange. It starts off very low and scales to costing over 100 mana at max rank. The reason for this, is that I generally want repositioning Shadowflames in lane to be basically free, but at the same time I want to gate Sheraze's ability to just max E and harass with it's low cooldown. As such, leaving it at one point and maxing other abilities provides a lot of utility at a low cost, and maxing it first is hard to sustain in lane.
Ultimate - Nether Gate: Picture Veigar's Event Horizon, but as an ultimate. That is basically what Nether Gate is: it creates a prison around an area, with walls that stun and damage things which try to pass through them. Unlike Event Horizon, Nether Gate will also stop any champion who gets stunned passing through a wall while dashing, in the same manner that some other hard CC ultimates stop dashes when used (Frozen Tomb, Nether Grasp). Also unlike Event Horizion, Nether Gate can stun and damage the same target multiple times. After the stun wears off, the victim is immune to the stun and damage from passing through a wall for 3 seconds, and if the wall still exists after that time they will be stunned again if they try to pass through. In order to make standing within the Nether Gate somewhat risky, enemy units inside also have their resistances reduced. Nether Gate also prevents flames it uses from expiring while it exists.
Nether Gate is targeted in a bit of a strange way: it would use a ground-targeted AoE targeting indicator, but would then function somewhat differently. When targeted on an area, Nether Gate will create the largest possible convex polygon in that area, using Shadowflames within the area as the points of the polygon, and will then create walls between those flames. Flames which did not have walls drawn to them (because they were inside the final shape) do not interact with Nether Gate. Upon selecting Nether Gate and hovering over an area, the walls which will be created are indicated to the targeting player. Obviously, since it is impossible to create a polygon with fewer than three points (a triangle), nether gate cannot target an area containing fewer than three Shadowflames.
Nether Gate also interacts with Sheraze's other abilities: Void Burst cannot target a flame used by Nether Gate since that would destroy the walls; Dark Lightning will act normally; using Shadow Rage on a flame which is part of the Nether Gate, will move the flame and the walls which connect to it. This allows Sheraze to change the shape of the gate after creating it, which in turn allows her to virtually guarantee a hit with one of the walls on a target by closing the walls in on them. Nether Gate has a fairly long cooldown given it's incredible power for teamfight disruption.
Sheraze requires three things to be effective in fights:
- Ability Power: so that her spells actually do damage.
- Cooldown Reduction: Her cooldowns are fairly high without it and her skills, especially Q and W, can be dodged, which will often leave her without enough damage to kill something in just one rotation.
- Mana: All of her mana costs are pretty high, and she wants to be able to use E as often as possible in an extended fight, which would quickly run her out of mana. Mana Regen could serve this purpose in lane, but would probably become inadequate when she actually tries to engage in a drawn-out fight.
Given the cooldown on E, Tear of the Goddess into Archangel's Staff seems like an obvious choice, providing Mana and a lot of AP while being easy to stack. Rod of Ages could also fill the mana + AP slot if she needed to be tankier, though she generally wants to be as far from enemies as possible so a tanky build seems pointless.
My full build would probably look like this:
- Sorcerer's Shoes / Ionian Boots of Lucidity: Penetration boots are an obvious choice on a mage, though CDR boots could also be used depending on her CDR needs.
- Seraph's Embrace: A massive chunk of mana and ability power. Given Sheraze's lategame teamfight strength, items which focus on a strong lategame should be pretty good on her.
- Athene's Unholy Grail / Morellonomicon: Both provide 20% CDR and some AP. I think that Seraph would be enough in the mana department and that Morello's could be picked up over Grail because it gives more AP, as well as being more cost efficient. Not sure about that though, either one could work.
- Rabadon's Deathcap: A no-brainer. She has fairly high AP ratios, and deathcap gives a huge amount of AP.
- Void Staff: Basically mandatory on mages lategame. Since Sheraze would generally take a back-line role, she wouldn't always get to directly choose her targets, and Void Staff would allow her to damage everything.
- Zhonya's Hourglass: An amazing defensive item that also gives a huge chunk of ability power. Go figure.