Alva & the Temple of Atzoatl
During the course of Act 7, you'll meet your next Master. This time it's Alva Valai, Master Explorer, an archaeologist of distant Vaal blood who is looking for a lost temple of the Vaal built shortly before their demise. She introduces a new mechanic called Incursions, where you manipulate the past to reap rewards in the present.
In the Causeway of Act 7, and randomly thereafter, you'll run into Alva in the open world. When you find her, she'll be in an area with three Temporal Incursions scattered throughout the map.
Incursions are small rooms that you get access to for a limited time, which can be extended by killing the monsters inside the Incursion. Monsters in Incursions do drop loot, but it's dropped outside the Incursion once you complete it, meaning you don't need to be looting while you fight.
Each room contains two things of interest aside from the general monsters: Architects and doors.
Architects always come in pairs at the lower-left and upper-right of the room. When you speak to Alva, she'll show you a map of the Temple as it currently stands, and the two Architects will be shown on this map. You can hover over the two symbols on the room to see what killing each Architect will do: it will either upgrade the room to the next tier of the same room type, or will change the room to a different type. See below for a list of the possible rooms.
Doors are located around the edge of the room. Killing monsters in the Incursion has a chance to drop a Stone of Passage or two (one is guaranteed if you fully clear the room), which can be used to unlock the doors. Stones are the only loot drops you'll see inside an Incursion, and cannot be brought outside of them. You can't pass through unlocked doors yet, but only doors you unlock during Incursions will be passable when you access the Temple later, so you'll want to use the Stones you find to create a path through the Temple to the rooms you want to access.
You cannot control which room in the Temple your Incursion brings you to, although Alva will show you which you're headed to ahead of time. Your choices lie in which Architects to kill and which doors to unlock. Before an Incursion you'll be shown a map of the Temple as you've set it up so far, as seen below:
This map shows the current rooms available, which room you're about to enter for your Incursion (in this case, the highlighted Rank 1 Storage Room located at the bottom left), and your options for changing the room (top right). If a room is already Rank 1 or higher, you'll always be offered the choice of upgrading the room to the next tier (the icon at the top right of the inset at the top right) or switching the room to a different type (bottom left). Decide which boss you want to do and which doors you want to unlock before entering the Incursion, and route your movement around the room accordingly!
Rooms that are accessible in the Temple as it currently stands are lit up; inaccessible rooms are somewhat greyed out. In the image above, most of the rooms have been connected to the entrance, only the Pools of Restoration at the bottom-right and the Apex at the top are disconnected.
As a general rule: during Incursions, you should prioritize making more rooms accessible first and killing the bosses second. A capable build, however, should be able to do both without too much trouble.
The Temple of Atzoatl
Immediately after you complete your 11th Incursion, you'll be granted access to the Temple built by your actions in the past. You begin just outside the temple and enter through the Entrance room at bottom-center, and can proceed through the temple through the paths you unlocked during Incursions.
The Temple operates on the rules used for Maps in the endgame: you get 6 portals in, and they're consumed when used, so you will eventually run out if you die frequently. Opening a new Portal inside just changes where you'll re-enter if you die or leave.
Inside the Temple you'll find special loot, depending on the rooms you've upgraded. You may or may not be able to access the whole temple, depending on your skill with choosing which doors to unlock and your luck with which rooms you had Incursions into.
At the top of the temple is the Apex of Atzoatl, which is not accessible through Incursions. It contains a special boss, the Vaal Omnitect, who is guaranteed to drop special Unique items and Rare items with special affixes. The Omnitect's drops are extremely strong when leveling, and it is recommended that you prioritize Apex access early on. In the lategame its drops can be a bit underwhelming, but Apex access is still a decent priority.
Once you've looted everything you want to loot and killed everything you want to kill, simply use a Portal Scroll to leave the Temple. Your next encounter with Alva will start with the first Incursion of a new Temple, and the cycle repeats.
Rooms in the Temple come in three tiers. At the start of your Incursions you'll have a mix of Tier 1 rooms and Blank rooms, and with each Incursion you can either convert the room you're in to Tier 1 of a new room type or upgrade it to the next Tier of the current room type.
Temple rooms come in a few main types (these are unofficial names):
- Blank rooms do nothing, and are there just as placeholders until converted to a different type.
- Temple Empowering rooms buff monsters in the temple, and reward a special item only if upgraded to tier 3 (either a special Unique, or a Magic item with special modifiers).
- Omnitect Empowering rooms are as above, but buff the final boss, not the rank-and-file.
- Loot rooms have, uh, loot. Each loot room has different types, and higher tiers of the room have more loot.
- Modifier rooms modify the entire Temple, generally in a mix of beneficial and harmful ways, with the effects increasing at higher tiers.
- A few miscellaneous rooms, like the Sacrifice room (which allows you to sacrifice a Unique item for a new random Unique or, at Tier 3, to upgrade Temple-specific Uniques).
Rooms with no stated effect will, generally speaking, have a reward at Tier 3.
The Temple is quite lucrative, and it's worth looting any of the rooms that have special loot.
Special rewards include:
The various loot rooms can drop special items, some of which break the normal rules of the game by dropping Uniques exclusive to past Leagues or items with more than the normal 20% Quality cap (we'll cover Quality a bit later in this guide).
Two rooms in the Temple offer the chance to Corrupt an item more powerfully than a Vaal Orb would. These special 'double corrupts' can apply two special Corrupted modifiers to an item (instead of the normal one), upgrade a skill gem in two ways, etc. But like a Vaal Orb, their effects are unpredictable and can be negative.
There are many Unique items specific to the Incursion league. Most of them can be upgraded using special Vials found as drops within the Temple by bringing both the item and its specific Vial to the Tier 3 Sacrifice room, the Apex of Ascension (not to be confused with the Apex of Atzoatl, the top room of the temple).
The Omnitect drops rare items with special affixes. These affixes are on par with the best affixes available on an item and have inherent no level requirement, meaning that many Omnitect drops can be top-tier leveling items. The special affixes are good enough to sometimes be worth doing special crafting with, as well.
Should I do Incursions at low levels?
Yes, absolutely, especially if you're new. The Omnitect's drops can be so powerful than you'll use them for the entire campaign, and the loot rooms can offer a tremendous amount of Currency items.
What does "Implicit Modifier Magnitudes are Tripled" mean?
This is a modifier that appears on the common String of Servitude belt dropped by the Omnitect.
Implicit modifiers are the modifiers listed first on an item, "above the line" above other modifiers. We discussed these in the "Items & Mods" section previously. The String of Servitude replaces the normal +Strength Implicit modifier on a Heavy Belt with a special Corruption-only modifier, then triples its effect. The value displayed is already tripled and won't be tripled again.
Is this String of Servitude good?
Probably relative to the items you'll level with - but no String you'll find until very far into the game has any chance of being particularly valuable.
Why can't I access this room?
Most likely, you failed to unlock the door during Incursions. You won't be able to unlock it in the Temple itself unless you have one of the rooms with gunpowder kegs in it (which can blow up one of the doors).
Do I need to clear the whole Temple?
No - just loot the rooms with special loot and kill the Omnitect, then leave.