These are all the mechanics You will encounter in Maps while playing Path of Exile. As there are way too many, they will be sorted by the order of upload (newest to oldest), because they need to be constantly refreshed due to new patch changes.
These videos should help You with understanding the base mechanics, what interacts with what and in what way to deal with those mechanics!

Essence

Harvest (One of Crafting Mechanics)

In this video, you’ll learn how Harvest as a mechanic works, how to deal with Harvest crops, collect Lifeforce and use it in the Horticrafting station, to change your Resistances or for other crafting purposes!

Blight (Tower Defense Mechanic)

This video will explain to you how the entire Blight (Tower Defense Mechanic) plays out and the ways to “Enchant” (anoint) our items!

Ultimatum

Ultimatum is a “wave” mechanic where we choose one negative effect (that stacks with other ones and in difficulty!) in order to pursue better rewards and ultimately, defeat the Boss of Ultimatum – Trialmaster.

Vaal Side Areas

These areas are influenced by the Vaal and you can access them via Maps themselves. Even if you die in these ones, you will respawn in the map itself! They give corrupted loot (vaal gems, vaal orbs, Atziri fragments etc…).

Shrines

Shrines are a “buff” mechanic in PoE 1. We click the shrine, we get buffed!

Rogue Exiles & Tormented Spirits

Beyond

Maps influenced by Beyond have a chance to spawn Beyond Portals (Red blood orbs) that will summon demons from other realms. It has 3 bosses.

Delirium

Delirium is a mechanic where we walk through a “Mirror” and become Delirious. We hunt our nightmares there.

Harbingers

Harbingers summon monsters from different realms and once those monsters are defeated, they drop Currency Shards.

Ritual

Ritual is like a shrine, where we kill monsters and get Tribute. We spend that tribute in order to get rewards.

Legion

Legion is a mechanic where we open a Monolith and release the monsters from Stasis, so that we can kill them all and reap the rewards!

Expedition

Expedition is a mechanic where we excavate (with explosives!) the Remnants of the Past. They give various buffs and have side-effects too. We use their artifacts in order to deal with the traders of Expedition.

Abyss

In Abyss, we follow along a line of cracks and pits, to destroy the monsters that spawn from underground. If we’re lucky, we can even find the 2 Abyss Bosses.