Phoenix does have awful scaling though, as most of its damage on singular unit will most likely be from the 10 second burn time (150 damage). The bombs themselves have so low damage and AoE and are so spread out that they are mostly just to tag units to ignite them.
3 Phoenixes can barely kill 3 reavers from a huge stack of reavers, which is better than trying to do same with 3 ravens as most of them will be nearly dead or at least half dead after the initial bombings.
Still, if we are looking for Phoenix reworks, here is some ideas:
Idea 1:Make it scale better. decrease the burn time and move the dame from it to the actual bombs.
However, for this to actually work, there needs to be either of the following changes as well:
1.Increase the AoE of the bomb explosions to ensure that they actually hit multiple enough units to make the 450 damage or so payload do more damage to groups of enemies compared to just using Ravens to bomb the target.
2.Increase the total damage of the bombing, but make the bombs spread so much more that trying to bomb singular units would waste most of the damage. Basically the Tremor treatment. Would have a high risk of turning into better Raven/Likho against all late game unit balls.
Idea 2: Make it scale less (my preferred). Most of the damage is moven to the afterburn instead. As a result, a Phoenix hitting and igniting raiders like Bandit would ensure it would burn down eventually, while being mostly harmless against tougher units.
The bad side is that bringing multiple phoenix would only help you if it lets you tag more units to burn them, though it would still be useful to have one coming and going to ignite stacks of units before the fire goes out to keep them burning.