Even though Grimstroke and Mars sounds as if the devs are trying to fit the police in there, worry not - there ain't nothing blue about Dota 2's new heroes. In fact, the theme seems to be quite the blood red theme to Grimstroke's ink.
Stroke of Fate launches a "path of ink" from Grimstroke's brush, where the ink slows enemies by 80 per cent and deals them 300 damage. The damage increases by 40 for each enemy hit so we guess that sometimes, you really should paint everyone with the same brush.
Phantom Menace is a single unit ability that deals 30 DPS and silences an enemy for 5.5 seconds. It cannot be dispelled but about three attacks should be enough to destroy it. If Phantom Menace survives the full 5.5 seconds gnawing on your behind, it will deals 360 burst damage and returns to Grimstroke, where you can expect him again soon. Note that if killed, the silence effect stops.
Ink Swell is a single target ability whereby Grimstroke silences an ally, granting it invincibility for 3 seconds. Enemies in the range of the Ink Swollen ally suffer ink tendril damage. A portion of this damage is re-inflicted after 3 seconds, when Ink Swell crescendos into a damage and stun blast.
Grimstroke's final ability is Soulbind, which sounds like a co-op wet dream. Soulbind basically physically prevents two allied characters from straying too far from one another, while making sure that each spell cast on one, affects the other player as well. If you disrupt the connection with magic, you'll be instantly bound to another, closest player.
All in all, while not overly scary right out of the box, there are more than a few pairings that promise Grimstroke to be headache material. I'm expecting the first nerf pls post by the morning.
As far as lore goes, Grimstroke was to be an arcane guardian of his people, only to end up being the culprit for their eternal corruption. He probably spilt ink all over someone's shirt, mark my words. Anyway, Mars is said to be arriving later this year, while Grimstroke is already available.