I've always wanted to make one of these. Just for the sake of having it. Rule #10 as follows though I didn't keep precise track of materials.

Process Part 1 (The cheap steps):

• buy an ilvl79 penumbra ring for 50 divs

• greater chaos spam until T1 cold/fire/lightning damage

• divine until close enough to max roll

• add 2 mods and desecrate and attempt to fracture

• fail 5x in a row (pain)

• finally succeed when I roll T1 cold

• greater chaos spam until I hit T1 fire/lightning

• finally hit T1 flat lightning

Process Part 2 (The cortisol spike):

I desecrate suffix with an ancient collarbone so I can get T1 mana regen. This is the only mod on suffix guaranteed to survive whittling. Now I only have to worry about my chaos orbs rolling prefixes. It took only one omen of light to get T1 mana regen.

Catalysing exalt with attack catalyst to see if I can lucky roll T1 fire or T1 phys. Didn't happen. I spent about 4 whittles with perfect chaos orbs before I got T1 mana. It has the same ilvl (75) as my existing T1 flat lightning. No worries, I can keep it and throw on another prefix to roll into my next flat mod. I exalt and spend about 10 more whittles before I land on T1 increased lighting damage.

Now I have to risk it. I have a 1/3 chance with my whittling to roll off my flat lightning mod. Luckily it hits the T1 mana. I keep going. 2 whittles later and I hit T1 flat phys.

Process Part 3 (Home stretch):

I annul my mana regen suffix. I desecrate prefix with an ancient jawbone and reroll until T1 flat fire. I believe it took 5 jawbones. I use my remaining whittlings to to get T1 all ele res (pretty sure it took 3).

I guess I should spam divines to get a really good roll but I'm basically out at the moment and it's decently rolled currently. If anyone wants to mirror this I'll do it for free (DM me on Reddit sometime within 3 days of this post).

I don't have the baals.

Edit: it's now divined to where the tops of each flat range are max rolled with the bottoms mid to high rolled. 29% increased lightning damage and 15% ele res.

POB: https://poe.ninja/poe2/builds/vaal/character/koroks-7678/lastlamenttitan

Video shows a T3 Xesht kill and a juiced T17 overrun map clear.

Core Concept

Stack as much reduced/less skill effect duration as you can on time of need to get thousands of life recovery per second. Use this to sustain last lament. Beyond this just try to get as close to possible to the feel of Sowza's 0.3 build.

Time of Need

100% reduced skill effect duration is only possible with a palm of the dreamer, which you can't use with a crossbow, but I can still get 92% from the tree. With overabundance 1 and compressed duration 2 I can get something like 2% skill effect duration on time or need. It's about 6k life regen per second with procs every 0.25 seconds.

Clear

I have 65% movement speed in hideout and have a decent amount of reduced movement speed penalty. I use galvanic shards with fork to clear maps. You can't get to the levels of movement speed that you could in 0.3 with Lich but it still feels good. Unfortunately the tree is all over the place so it's hard to max out movement speed.

Single Target

Emergency reload to empower bolts, elemental weakness to reduce elemental resistance, and then let loose with requiem.

Defence

I stacked life and got an undying hate with loyalty to amanamu to get sacrifice of flesh. This essentially gives me 20% damage reduction. With the ~6k life regen per second and immunity to curses and elemental ailments, this is quite solid, but I can still die in extreme circumstances. Olroth's resolve is recommended to give you a bit more max hit.

Gear

Defences don't matter in this particular build so just go for as much life as possible. The crossbow has a 5% crit chance so scaling crit is pointless. Especially with how stretched thin the tree is. When buying the crossbow go for as much DPS as you can afford. If you want to spend you can buy one with level 20 requim to get that 5th support gem slot.

Damage wise, vertex and Sacrificial regalia are great to get +skill level. I went for the non-unique sacrificial regalia so I could get life and spirit. Flat damage is good on rings, and since you're stacking life you can go for bursting decay, which scales flat damage off of your life. I use headhunter but if you don't like it you have a few more options:

• ingenuity: boost rings = good

• darkness enthroned: you can get 12% increase max life with jiquani soul cores

• rare belt: go for as much strength and life as possible.

Thoughts

Fun build, very solid. This build probably isn't going to be possible next league due to reduced skill effect duration shenanigans almost certainly getting nerfed. I haven't put that much thought into min maxxing so let me know if there's something I can optimize. I don't know jack shit about crossbows.