Easy ones variants to depict are small bat-like wings or the cloven hoofs that were on a lot of Tieflings in 2e. Or only having tails or only just horns but not both.
More subtle ones would be looking just having 6 fingers as a feature, as they are a lot of Tieflings that are descendants of...
So far the only the only place in 5e art where there's been different looking Tieflings has been in art related to Planescape, with one of them being from Diterlizzi and the other one of Factol Rhys.
Planescape
Player book
Planescape probably does need something a little more player focused maybe like that delayed Forge of the Artificer book. It can be a supplement to the existing PS Campaign setting like how Forge of the Artificer is supposed to be to Rising From the Last War.
The player...
One thing that occurred to me with the Storm Herald Barbarian is what happens when you throw a 5 foot block of ice? It's completely doable at 6th level with the Storm Soul Tundra ability, even if it might not be a common thing that happens.
I think it also brings up something I expected when they changed the name of Monk subclasses to "Warrior of _______" it would definitely force a rename of some subclasses. Kensei will probably be affected by this naming change too.
Drunken style kung fu was about imitating drunkenness not actually being drunk. While the subclass has been about actually being drunk, so intoxication was probably a clarification on that
This isn't much different from all those who were claiming that all D&D is Planescape because it uses the Multiverse and the Great Ring Cosmology.
Sigil has portals to all sorts of places in Toril and especially Faerun. An official 2e adventure module has the Modrons use a portal through...
It looks like additional casters doesn't boost the spells slot level, which I guess is good for preventing things like a Fireball inflicting 30d6 damage. Instead it seems it might have an effect like a Fireball that has a radius of 300 feet.
Though it's definitely other spells that aren't...