Ignite enjoyers what are we thinking
How are we setting the screen on fire this league?
Without Elementalist, we (mostly) lose the ignition with other elements part. I guess there's Hexblast if you don't mind the long cast time. I am also not putting FF/FF into consideration.
Here's some of the cooking so far:
Architect: Vaal Flameblast is huge, and VFB+defiled forces is one of the key single target for spell ignite builds. The ascendancy gives many ways to push VFB, through increased crit (enabling EO), gem levels, and QoL for being able to cast it more often. Glimpse Chaos gives you a massive amount of HP and ES. This feels like the comfiest and simplest scaling ignite.
Polytheist: Level 20 Aberrath's Fury has the potential to be extremely goofy for a skill-less ignite build. Unfortunately, it cannot be supported by anything so I'm not banking on it. There's some great QoL on the tree, min charges, hexproof, and immunity to ground effects. Could be fun for mapping.
Bog witch: 50 inc aoe and 40% more DoT are good but nothing too crazy. Here's where it gets spicy though. Fell Fen + Blackflame + wither stacking. This is potentially more damage taken compared to the typical double curse path. However, the burning ground that flame surge creates is still fire.
Wildspeaker: This one's a bit unhinged. Scourge of the Wilds give the same benefit as The Scourge claw, which is common on Maw of Mischief builds. This means potentially going 2x Scourge (if that works) or if it doesn't, using a huge minion/fire dot wand and benefit from this tag. Primal instinct is a good suppress node IMO, and you can either go the aspect of cat path (more damage/crit) or aspect of avian (more ms). However I don't think it will be better than normal Maw Elementalist, who has access to -res and shaper of flames.
Other stuff, welcoming your wild ideas:
Whisperer: I feel like there's a mana-stacking attack angle with Manaforged Arrows but I am not 5Head enough to figure it out. The asc is designed for hit builds in general.
Paladin/Aristocrat: Both of them have good ele damage support (Dreadful Attitude and Paladin's entire left side). I think something like EA can pop off on either. However, leaving the Duelist area is kind of hard.
Ancestral commander: Is so tanky and you get +3 endu charges, are there any ignite skills scaling endurance charges?