User blog comment:Jomariski/Grim, The Messenger of Death - Champion Concept/@comment-3391671-20170615030329

Another Death based champion. Well, there is always room for more death, no?
 * Statistic aren't there, neither the roles. I presume you didn't have any in mind?
 * Based on the ratings, and that the concept is death, this champion is an Assassin-Fighter. Well, hopefully, the kit proves to support that fact.
 * While scalings are not always necessary (and being something more recent compared to older champions), I recommend having scaling values in the innate. Spices it up and lets the summoner know that as the game gets longer, the champion's powers grow too.
 * For an innate, Closer to Death is nice. Not exciting, but surely not overly underpowered nor overpowered. It's just simple and brings little exciting. It's effect helps if you can land three abilities from your kit on the same enemy, them for a moment. The fact that it's champion-only makes it less for lanes and more for ganks or teamfights.
 * I notice now that there are missing parameters. I really should get onto that guide on Custom Content creation (and I say that all the time too).
 * Dark Claw seems to be a basic offense ability in the form of a skillshot. It has a medium cooldown, with the ability to be recast (without cost) if the ability successfully hit a champion. This seems like a nice and simple ability, although more could be done to make it exciting.
 * Lesdin said there was no ranking incentive before for W, but I presume you made a change since he made the mention.
 * Death cannot Die is a CC immunity spell that also reduces the caster's damage... which I find unusual. Even with the recent addition of, reduction to one own's damage dealt is rare, most especially not implemented on someone who is likely an Assassin. Even if a fighter, the champion is supposed to deal damage, and to have it reduced seems more like an MMO implementation than a MOBA one (more about balance than class focus). The spell itself could receive some workings on it, or looking at its title, it could be the ult.
 * League has been consistent in having ability have scaling values. Even for the innate abilities of a champion, unless scaling would grant too much power, they will change over time. Here though, Message is an active ability... and has no scaling incentive as Lesdin mentions. The "no rank in one ability" is getting old as its often done on shapeshifters, and even with 's new kit, it feels like a cop-out.
 * Message as an ability feels like a forced "in, then out" ability that is supposed to rewards proccing Grim's innate by letting him have a way out. Without ranges and other details, it's hard to judge this ability, so I recommend that for all your abilities, you are more specific with what the abilities do. Look at other champions for what I mean, since official ones state more than "they teleport in and teleport out." Also, in this case, the right term would be "blink," not "teleport" as the latter is strictly for a summoner spell.
 * I feel like a broken record, but while a nice idea, A Visit by the Messenger pales as an ult. It's not broken, neither is it underpowered, but surely, it doesn't feel much interactive. Mark a target, hit three times for max damage from this ult, voila...
 * Looking at the damage, maximum damage is 490 / 700 / 910, which isn't too large. I do not mean to say to increase the damage, but looking at Grim's kit, it's possibly easy to reach this maximum damage without a sweat.

The kit isn't terribly unbalanced, but a mix between lack of information and interesting (or cohesive) mechanics, there is much that can be improved.

Now, a little criticism on the short you had supplied. Although I will guess that it was added to give a little backing to this champion instead of giving him a blank face with the death theme, the story could also be improved. As of now, the backstory is as simple as "a great hitman died, was elected by the God of Death to be his messenger of death... and that's that." I would think the God of Death would elect the or even  to do this job instead of some hitman who died from being outnumbered. His backstory does not put the "legend" in "League of Legends" if I were to be harsh. What is impressive is that the God of Death chose him, but from a big picture standpoint, the story feels like it entitled the role to the hitman, not the hitman attaining that status because he deserved it. This is where you need to be careful with lore building, as it makes the character less believable, or forced in some respect. Putting gods into the scenario also is a literal Deus ex machina cop-out of its own, and becomes terrible if it becomes the only justification of the scenaria, thus a flat out excuse to make someone a champion.

Therefore, I recommend writing the lore around something else. As of now, the Hitman is no more than a no-face with no personality and no possible attachments we readers could ever make upon the man. Most especially, he is not a legend at all.