While Tourmaline requires merely an equipped Stone Mining Cell to be mined, you will need at least an Iron Mining Cell to dig through Igneous Rock, Hardened Lava and Sulfur. Diamond Ore can be extracted from Diamond Nodes only with the help of Extractors of any kind.
Hot Feet and Warmworms are able to spawn in the Lava Layer during day and night on all blocks that are not illuminated by artificial lights or sunlight (if players should dig shafts leading down from the surface to the Lava layer). Hot Feet and Warmworms seem to be immune to fire, and Hot Feet can sometimes seen crossing pools of liquid Lava unfazed.
Neither the glow of Hardened Lava blocks nor the brighter illumination of liquid Lava will hinder these Creatures from spawning. However, if Hot Feet are hit by sunlight, they will burn away in blue flames. Iron Treasure Chests are able to spawn on all blocks that the Lava layer is made of, unless in areas illuminated by artificial lighting or sunlight.
Sometimes, green Mirus will venture down into the Lava layer, and Keepas of any kind can also spawn there. However these Creatures can actually start to burn in time or when touching liquid Lava, which indicates that they too might even have their own heat meters.
It is advisable to stay away from pools of Lava, because as soon as player characters touch liquid Lava, they will immediately catch fire and suffer from fire damage over time for ca. 3 seconds even after stepping back. However liquid Lava is not instantly deadly, but usually leaves player characters enough time to find an escape or gulp down Basic Health Potions or Advanced Health Potions to stay alive.
Armor does not protect player characters from heat damage and does not reduce it either; since currently armor only protects from physical damage.
Temperature on the Lava layer is very high. Just by getting closer to hot Hardened Lava rocks or liquid Lava will already make a heat-scale show up that will then fill itself with red color for as long as you venture in this hot environment, until your player character will start to burn if no counter-measures are applied in time.
In order to reduce the heat that the player character "feels", it is not sufficient to simply step on cooler blocks, since the whole surrounding (even blocks above the player character's head) is contributing to the total temperature that affects your player character.
To deal with heat meters, Fire Resistance Potions can be crafted and consumed. They will grant "immunity" to the heat for 10 minutes - indicated by the heat meter going down, vanishing and not showing up anymore for the whole time (even though the description only promises 90% reduction), and the potion will also reduce all fire damage over time (as dealt by Hot Feet, Warmworms or by touching liquid Lava) by half.
To reduce, negate or even reverse fire damage over time into healing effects, different kinds of Food can be cooked in the Cooking Station. Blazing Sandwiches and Blazing Pie will reverse fire damage into healing over time, but will not make the heat meter go away; both require liquid Lava as their main cooking ingredience.
An easier way to deal with the rising heat on the Lava layer is to simply dig ascending steps into any solid wall and such enter the Stalactite layer in order to cool down for a while before descending again after the heat meter has gone away.
Also digging downwards into the Corruption layer (as far as necessary for the heat meter to sink) is an option to flee the heat, however it is not advisable to stay close to corrupted blocks for too long, since Corruption will deal damage over time too as soon as the purple corruption meter will be filled...
In larger caves with a high ceiling or a ceiling consisting of Stalactite layer blocks, it is sufficient to stack at least 3 non-flammable normal-temperatured blocks on top of each other and to hop on top, or to place at least 3 Stone Ladders or Industrial Ladders onto the ground and climb up to make the heat meter go down. Just take care not to stay or get too close to any "stalactites" or cave ceilings consisting of hardened lava, because this will not let the heat meter drop.
Hardened Lava can cool down and turn into Igneous Rock when it is cooled down - like when placing only a few blocks of Hardened Lava into cool areas) or when hit by Freeze Bombs, or even when ordinary Water is placed on Hardened Lava blocks.
Hardened Lava will also turn into Igneous Rock when being placed into cool environments, which can be prevented by placing more blocks of Hardened Lava together. This will enable them to prevail even in cold biomes and make them heat up the direct surrounding too.
If placed into liquid Lava, flammable materials like Leaves, Shrubs, Shredded Leaves, Thatched Walls, Wood blocks of all kind (even Corrupted Wood nowadays if placed in small amounts), Corrupted Leaves, Wood Walls, Wood Ladders, Wood Doors, Wood Tables and other wooden or vegetal blocks and items. Not every plant, block of plant origin or object made of wood is flammable though.
Mineral Water, Bog Water and Corrupted Water will evaporate if being placed on or next to liquid Lava in a small enough amount, otherwise the liquid Lava will harden into Hardened Lava instead. Molasses neither burns nor evaporates.
In the overall heat of the Lava layer, blocks of Hardened Lava can set flammable solid blocks and items on fire, but not all of them start to burn equally easily. Hardened Lava can even set flammable blocks and items on fire in cooler biomes, but usually only if objects that operate with fire like Torches are being placed close by or even below the flammable objects/blocks.
Throwing Freeze Bombs or placing Water or other Liquids except for the highly flammable Tar will transform liquid Lava into Hardened Lava, which will also happen if you liquid Lava into cool environments. To prevent Lava from hardening, you will have to heat up its surrounding by placing enough blocks of Hardened Lava together.
If you place blocks of Snow or Ice into the Lava layer, especially on Hardened Lava or liquid Lava, they will melt into Water, which will also cool down and transform the hot blocks/liquid. Snow Cap blocks will merely turn into common Dirt blocks in the heat of the Lava layer. Blocks of Sand will turn into Salt when being surrounded by liquid Lava at least on 2 sides (preferrably 3) in a hot enough environment.
Hardened Lava is a Level2-Fuel that will need only 30 seconds to melt 1 Lumite Ore into 1 Lumite (bar), however 4 blocks of Hardened Lava are necessary for each process (while only 1 Coal or 1 Sulfur has the same level of power in the Forge). Food made with Tar can