Hello everybody. My intent in making this guide is to show people how awesome AP Squire is :).
I don't know everything about this build and how to fully maximize it because I couldn't find any guides on this topic and that is primarily the reason I am making this guide, to give information about this build to people that need it. If I made any mistakes or you have any suggestions please PM me or post below :).

Ability power squire is a very viable build that can be built in two ways, Ability Power+Hero Crit Damage and Ability Power+Hero Health. In this guide I will be focusing on AP+HCD since it has higher damage output.

I don't have the best squire gear, but my current damage numbers are:
- ~45K Unholy Fire damage (Sustained Damage)
- 458K - ~6 Million? Seismic Slam damage (Burst Damage)

Seismic Slam does more damage to farther enemies from you. At the point blank by slam does 458k, the highest damage that I got while testing my damage was 6 million, but it was very hard to achieve that since the range where the damage gets boosted by a lot is very very small. I will try to explain it in this way: Imagine a circle, now of we draw a line from the middle of the circle to the edge, in the first 90% of the length of that line from the middle, the damage increases from 458k-900k, In the 90-98% range the damage increases to 1.5 million, past that, the 2% that is left, the damage increases greatly. Trying to hit that 2% on purpose is almost impossible, and you will only hit it if you are very lucky.
With some training you will be able to aim for the over 800k sweet spots.
Having a dragolich will make this build much more fun and viable, because with him, you can easily get 1.5m+ slam damage.

Let's get onto the main part now :).

For this build to work, you will need to get the Sword of the Unholy fire. It drops from the Unholy Catacombs Challenge.
It would be nice (not must) to get the Harbinger shield that will reduce your Seismic Slam cooldown after you blocked damage with your RMB.

For stats you will need to get:
- Ability Power
- Hero Crit Damage

Optional (Very useful to have):
-Hero Health on your shield

Best passives to have:
Hero Crit Chance (Helmet, Chest, Boots, Gloves, Relic)- Needed to proc your second stat.
Life Leech (Weapon) - Very useful since it proc's on the Unholy Fire passive, so you will be blocking damage, dealing damage and healing at the same time.
After Shock (Shield & Relic) - Useful stat to have, it prolongs the Seismic Slam stun.
Regeneration (Chest) - Good for additional healing effect.

If you like to spam the Seismic Slam/Sword(Empowered) Beam:
Super Conductor & Chanel (Helmet, Chest, Boots, Gloves, Relic)

Optionally:
Full Hearts (Helmet, Chest, Boots, Gloves, Relic) - If you like the Sword/Empowered Beam Spam and want to do more damage by it.

Also don't forget about your gear resistances, if you are going to be directly blocking enemy damage (aka. being a wall) and wont be trying to kite it, make sure that most of your gear has physical damage resistance.

You can find a very useful spreadsheet about passives here[docs.google.com].

This is my Stats and Sphere setup.