Tank Zaahen Build

1. You start with Guardian's Horn. Your #1 rush should be item that counters enemy team most (MR or Armor item). Get Jak'Sho as #2 item. Then adapt.
2. Triumph is better overall (heal + gold), but if you want to have easier time with your mana, go Presence of the Mind.
3. Guardian's Horn is a surprisingly good item for its price. You can keep it for very long time (or even have it as 6th item).
4. You need to adapt your items to the game. Enemy team heavy on AP? Buy MR. They heavy on AD? Buy Armor. You need some damage? Well buy that.
5. Be careful to not waste Aftershock. Try timing it and keeping it for going in.

Cultivation of War (Passive)

1. Passive stacks much faster when abilities hit multiple targets - Dreaded Return (W), Aureate Rush (E), and Grim Deliverance (R) give extra stacks per champion hit.
2. Always weave auto-attacks between abilities to maintain and build passive stacks.
3. You can be way more aggressive when passive is at max stacks as your revive gets available.

The Darkin Glaive (Q)

1. The Darkin Glaive (Q) is an auto-attack reset. Auto attack first, then use Q to reset and attack again immediately.
2. You can insta knock up enemies. Prepare Q2 beforehand (i.e. on minions), then activate it, issue attack on the enemy and Flash for the sweet CC.
3. Use The Darkin Glaive (Q) to sustain.

Dreaded Return (W)

1. To ensure your W hit, first knock enemy up with Q2.

Aureate Rush (E)

1. E can be used as a short dash or canceled entirely when used around walls.
2. You can use E + Flash, but you need to do it at right time at very last frames of the ability.

Grim Deliverance (R)

1. Grim Deliverance (R) is very versatile tool. You can use it offensively to initiate or defensively for survivability or escape.
2. As your Grim Deliverance (R) provides 50% damage reduction during cast as well as healing, you can use it as crucial defensive cooldown in fights. Don't waste it at maximum health, but time it well, for example to survive burst.