well, for a quick review, Amistaad's kit doesnt seem to come together very well. For starters, his kit doesnt seem to fit your theme of an adc that splits enemies up. he has a turret (the tesla tower), a bomb that chases people down, a melee stun for 3.5 seconds at max rank, and then an ultimate that makes him invincible for up to 9 seconds. The kit doesnt seem to fit the theme very well. I feel this concept also occupies a thematic space that Viktor already does, that of the Cyborg / Android / half human half machine character. I also see you possibly reference Viktor himself within the lore.
As a marksman concept, he lacks any attack speed steriod, which sets him back a little bit from other ADCs, and high base damages on his spells, which with any kind of decent ad scaling would put him over the top just by themselves, not considering his ultimate. The concept of an adc that splits enemies up during team fights is a good one, examples of such would be Varus and Miss Fortune to a degree :)
Skills overview:
Passive: ?
I think you forgot to write out what Amistaads passive is ^.^
Q: Hextech Sweeper
I think the concept is an interesting one at its core, something to use to find an enemy, with the added bonus of aoe damage. There is precedent for giving ADCs a skill to help scout, ashes hawkshot, kalistas sentinel, etc. I feel that this ability would be good if you played around with it, possibly having it stay still until an enemy wanders too close to it, after which it reveals them and attempts to detonate on them, or have it travel to the location you point out, and if it comes near an enemy champ, it reveals them and chases / explodes. The base damage is very high, starting out at 100 damage at level one, and its mana cost is pretty expensive, so you would not be able to use it often. If you can flesh out the ability some more, like cast range, It would reveal more of its purpose, right now it seems to be a skill you use to keep vision on an enemy when they run into the brush. Also there is an item named Hextech Sweeper already, its available on the dominion, twisted treeline, and I think the ARAM map as well ^.^
W: HexTech Tesla Tower
I am not sure what this is intended to do for Amistaad, and the wording is not as clear as it could be. Does the tower attack everything in range or only one target? How are targets prioritized? Can it be destroyed and how resilient is it? Does he place it where he stands or can he place it from range? The ability is on a long cooldown, so its not something to be used incautiously. I imagine its some sort of tool to either zone or to throw down when someone all ins and make them regret it, a la Heimerdinger. The tower bolts deal magic damage, and if you rank it up first I suppose it would be strong in certain situations, but that would require your enemy sitting under it to take multiple bolts. The towers damage also presumably would scale with AP, not AD, and would therefore fall off in the mid game, acting more like a light DoT effect than anything.
E: Tesla Blade
Looks to be a frontal cone stun perhaps? Also does magic damage, so we run into the scaling issue, base damage starts out low but quickly ramps up with ranks, as well as increasing the duration of the stun. Can it stun multiple people? From your description I would hazard a guess and say its a multi target stun. I personally dislike crowd control that lasts longer than 2.5 seconds, as after that point your enemy is usually dead or severely injured before they ever get out of the crowd control. It gets pretty expensive to cast as you rank it up, but I dont think that would counter the attractiveness of having a 3.5 second stun.
R: The Ultimate Machine
This ability has the biggest allocation of his power budget, 9 seconds of invulnerability at max rank, Double damage for attacks and abilities, and he also becomes solid gold hehe. Thematic issues aside (why would "The Ultimate Machine" be made of gold ^.^), this invulnerability lasts 6 seconds longer than Kayle's maximum rank ultimate, and Doesnt have much counterplay to it other than run. It would take more than a full team of 5 hard crowd control champions just to keep Armistaad down during his ultimate. Double damage for 9 seconds is also pretty strong, with a AD/Crit item build, you will be one or two shotting even the heaviest of tanks, and just downright obliterating any squishy you can reach. I would recommend scrapping this ability completely, and coming up with something that fits his style and has some sort of counterplay ^.^
Kit Analysis:
He needs a passive first off, something tied to his theme, something other than a flat boost to his stats. Suggestions include some sort of rhythm mechanic, something that encourages taking risks, or some sort of third resource to manage.
Amistaad's Q has potential, just need to flesh it out some more, and figure out what it should do that makes it unique to this champion.
Hextech Tesla Tower(W) is a little undefined in its role. Is it meant to be used to help cover your escape, or to zone your enemies? Or is it a tool to add more damage when you stun someone, or to punish people who try to All-In you? Turrets are sort of Heimerdingers theme, and short duration zoning tools are more zyra / azir territory. This also encourages Amistaad to play defensively, unless he can throw this tower down from a distance. If you are really attached to the idea of Amistaad having a turret he can throw down, you might want to look into how it should be unique and different from the above mentioned champions, possibly look into something that provides area crowd control, to help divert enemies away / around it, like viktors Gravity Field. Also think about when the opportune time to use it would be and how his fighting style should flow around it, rather than it being just a tacked on damage source that falls off late game.
Tesla Blade(E) is a short range multi target stun from the sounds of the description. Having a stun on a Marksman is problematic, because marksmen have incredible scaling by nature, and in order to make a stun feel "good," a significant portion of the power budget has to be allocated to it. This leads to a situation where he either has a good stun that is impactful, and has to use it to get the most out of his damage, or his stun feels weak and tacked on, and really becomes superfluous, giving him additional power without really increasing the enjoyment of playing him. This is also a close range ability, and to use it you have to have an enemy in your face, which is usually something you try to avoid when you are an ADC. I can see it as a possible escape tool, but the stun duration is so long you and your teammates will severely damage and possibly kill any enemy you catch with it, leading to a situation where you are purposefully trying to get in peoples faces to stun them with this. If you are looking for a disengage tool to get people out of your face, try a short knockback instead like jayce's Thundering Blow.
Finally, we come to The Ultimate Machine(R). This ability is very unbalanced in my opinion, due to the long duration invulnerability and the double damage. There really is no counterplay to it, your enemies have to either run or die, and those are both poor options. There is no way to outplay an enemy who uses this ability, its basically an "I win button." I would recommend scrapping this ability, as to make it feel even remotely good, you would have to strip power from every other ability in the kit just to give him something more like 2 seconds of invulnerability with no damage boost. The other option would be to turn it into a free Zhonyas, where he cannot damage or be damaged for 2.5-3 seconds, which would be an interesting space to play in for an ADC ability, but I dont think that is what you were going after.
Thanks for posting your champion concept ^.^ The picture looks awesome, and you gave the concept some effort, adding in lore, skin ideas, playing recommendations, mana costs and some cooldowns. :) Try adding in some base stats, ability ranges, auto attack range, cooldowns, and other things to further flesh out the character ^.^
Choc
Passive: Tesla Rising: When Amistaad kills a unit, he gains a stack of Tesla Rising. For each stack of Tesla Rising, Amistaad gains 0.5% attack speed. When Amistaad kills a champion or epic monster, he gains 2 stacks.
Q: Tesla Sweeperr: Amistaad throws out a sweeping lens that moves in a line. If the sweeper finds an enemy champion, it will follow them. If the sweeper reaches the champion, it flies over there head and primes for 3 seconds. After priming, the sweeper will detonate, dealing 35/40/55/60/75 After 5 seconds, if the bomb doesn't find a champion, it explodes. Cost: 2 Tesla Rising stacks
Cooldown: 17/15/13/11/9
