Guide

As I see many grim players build him completely wrong and losing the game due to their builds I decided to take matters into my own hands.
Grim is an immobile hard carry with good self peel and very high dps and burst, the purpose of this build is to play into his strengths but also try to deal with his weaknesses.

General tips

The thing that sets Grim apart from other carries is that his attacks will convert into magic damage, allow you to melt tanks that focus on building physical armor. Even big HP pools will rarely be an issue since your late game crits are so insanely strong. If they build magic armor we itemize against that with Caustica

Grim has great hybrid scalings, allowing you to be very flexible with itemization.

You are the carry, you are immobile, stay behind the tanks/bruisers and with your support.

This build gives Grim a bit of tankiness with World Ender and also Terminus for lifesteal/sustain in fights, you won't be too easy to kill but utilize your range and kiting with your slow in Assault mode (E).

Items

Learn to check the enemy items and itemize accordingly, item order varies

1. Dust Devil

• Damage
• Attack speed
• Crit
• Movespeed

Great first item since it gives you a good amount of important stats, allows you to kite more efficiently from the extra movespeed and also seriously boosts your attackspeed

2. Imperator

• Damage
• Crit

Amplifies your crit damage.
Every other hit (potentially since you are at 50% crit chance) will deal just massive damage.

3. Terminus

• Damage
• Crit
• Life steal

Sustain and a bit of shield, also ups your damage and crit chance significantly. If you are getting bursted by enemy magic damage you can opt for Absolution or World Breaker here instead, for some extra Magic Armor or HP.

4. World Breaker

• Magical power
• HP
• Tenacity

Straight up damage amplification since your attacks all deal magic damage, other carries will be jealous of this. 30% Tenacity is really not something to take lightly either, it will allow you to survive much more easily paired with the extra health this item gives.

5. Caustica

• Magical Power

40% Magical pen, this is very much necessary if playing against tankier heroes who items with magic resist, sometimes this even needs to be 3rd or 4th item.

Skill order and kit

I'm not going to list all the stats on every ability in his kit, but I will tell you a few things to keep in mind about them

Passive - Pulsefire

Remember to cycle between enemies if possible to proc your passive with two autos, also remember that Q+auto-attack / auto-attack+Q is a good poke combo since abilities apply and proc your passive stacks as well. You can also do a long range finisher with Q + Ult to make the ult proc the passive

Q - Displacement Blast

Important to note is that your Q only CCs in Assault mode (E). It will be lobbed in assault mode so aim carefully.
Your Q is your only form of hard CC and you should use it either to peel yourself by shooting it at the ground between you and a melee hero, or to push targets closer to you/your team by shooting it behind them.

This is also your primary poke ability, you should shoot the waves in sentry mode to gain mana back, then toggle to assault mode and then shoot your Q from a looong range and poke the opposing laners, this is the reason that you are going to max this ability first. It has great base damage and scales very well both from physical and magical damage.

E - Assault/Sentry mode

Basically, almost always use Assault mode when fighting enemies, when killing creeps/minions toggle to sentry mode to restore mana.
Simple as that. Of course there are exceptions if you need a bit more mana for Ult or Q in fights then of course switch to sentry mode. But this ability is one of the parts that make GRIM.exe a kiting machine

RMB

Note that this spell has a long cooldown so make sure to use it against high value spells, or for mana regen if you feel safe in your position in lane.
Don't be afraid to use it, this let's you play a bit more aggressively when you have it up against heroes with long cooldown CC like Riktor's hook. Try to use it for mana reg by walking into Murdock traps if it's safe to do so, prioritize using this for blocking CC. Some examples that come in mind is, Steel Ult, Khaimera Ult, Kwang Q. Learn the other heroes kits and what spells they rely on and block them, it will be GG.

R (Ultimate, G.T.F.O)

A very strong ability, long range and massive burst that scales insanely well with physical/magic power. Combo it with your passive or just use it as poek on the enemy squishies late game, it can easily deal half the HP of an enemy carry and in fights you don't want to be using it except from a safe position where you can't dps reliably. It will SLOW you 60% when you are channeling it allowing the enemy to jump you. In that case it's better to just DPS with auto-attacks.