here is an old concept of mine i made around the time it's rework got announced
https://boards.na.leagueoflegends.com/en/c/gameplay-balance/01bTEF5a-sunfire-cape-rework-concept
Short version 12-29 damage is now 13-30 still + 200% bonus vs minions
same range
But combusts after you get hit 5 times with a small delay and some sort of increasing glow to warn enemies and the co,bustion has a 50% larger radius then the regular burn
Combustion deals 5x damage so up 150
Stat changes
450 Health
45 Armor
100% health regen
Less armor but some extra regen to help with early trading in lane
One of my biggest problems is the extremely short range starting from hirbox center rather then edge which means if your champ is big like sion or cho you hit them with basic attacks before you can so much as scare them with your aura range
Looking back on my original concept one could fix the aura so it's better on bigger champions, like tanks, instead of it being worse
Reduce burn damage further to like 20 but increase the bonus damage to minions to 300%
Then up the combustion effect by letting it keep the 50% bigger radius and making it deal like 10x damage after you get hit 10 times it could even have a health ratio or add a debuff etc etc whatever it takes to prevent abuse although requiring the taking of attacks already sort of does this
In the 1v1 it takes a long time to trigger so it wont add much dps or use there
it keeps the wavepush element
Early game use is back but at the cost of armor in that particular slot although it should give enough for the early game
It restores teamfight use as far as damage goes, the counterplay would be to not damage the tank and thus requiring you to play around them if they bring a sunfire
Or you could simply keep an eye out for the combustion and avoid getting hit by it
So that would make it more interactive to play around
ofc the effect/damage would have to be tuned so it's not oppressive early nor weak in later teamfights as it would now have appropriate counterplay