Out With the Old
Plane of Fire
The safest part of the plane of fire is the Fountains of Creation, just before they become the Plane of Magma.
Out in the cinder wastes, a nomadic tribe of elemental creatures of smoke and ash travel, led by Gazra, the Shifting Emperor, their sultan. Gazra frequently clashes with Ehkahk, the Smoldering Duke for command of creatures of smoke.
Optional Rule: the Cinder Wastes
The Plane of Fire is unbearably hot. Anyone caught outdoors for more than an hour must make a Constitution saving throw each hour or gain a level of exhaustion. The DC is 5 for the first hour, and increases by 1 for each hour thereafter. Anyone without access to clean drinking water has disadvantage on the saving throw, as do characters in heavy clothing, or wearing medium or heavy armor, and anyone engaged in strenuous activity such as running or fighting. Creatures with resistance or immunity to fire automatically succeed on this save, and creatures naturally adapted to hot environments have advantage on it.
In addition, the Cinder Waste is filled with burning embers. At the end of each turn a character spends in direct contact with the ground, it must succeed on a DC 15 Dexterity saving throw or take 4(1d8) fire damage. A creature that ends its turn prone instead takes 6(1d12) fire damage on a failed save. Creatures with resistance or immunity to fire damage automatically succeed on this saving throw, as do characters wearing appropriate protective gear such as thigh-high fireproof boots.
Strong winds sometimes stir up the embers as well. In addition to the normal effects of any such winds, including natural winds, spells such as gust of wind and an air elemental’s whirlwind ability, they kick up a “cinder storm” within their area. Within the area of the storm, all creatures must make a Dexterity saving throw; the save DC is 10 for a natural wind or any other effect that does not list one, or the same as the regular spell save DC or other saving throw DC for any power that requires a save. On a failed save, the creature takes 11(2d10) fire damage and is blinded for 1 minute. On a successful saving throw, the creature takes half damage and is not blinded. A blinded creature can make a Constitution saving throw against the same DC to end this effect on itself. This effect is repeated for each turn that the wind persists and the creature remains within the area. Again, creatures with resistance or immunity to fire automatically succeed on this saving throw.
Optional Rule: the Sea of Fire
Each round a creature spends in contact with the Sea of Fire, it takes 22(4d10) fire damage. If immersed in the lava, this damage increases to 44(8d10).
Optional Rule: Scalding Walls
The walls of The City of Brass are always searing hot. Any creature touching the metal takes 4(1d8) fire damage. Any creature adjacent to the metal as it is tripped or shoved must make a DC 15 Dexterity save or touch hot metal, taking 4(1d8) fire damage.