To conclude Jorumn's history and throw him into the story a little easier, I'm intending on having him open a Warp Gate, though by unconventional means (if there's a conventional way) in order to escape his world. I don't want to put out details, since I want whoever reads the history to read it unspoiled, but I have a massive power source, and a fairly plausible way to protect him physically and mentally as he goes through it. It will be a one-time thing that he won't likely be able to repeat, and he'll come out the other side in... well, not the best of conditions.
I don't want to butcher any previously written things about the Warp when I do this, so I want to make sure I have everything down. My questions are:
-What is required to create a Warp Gate?
-How long could a mortal human with a strong will and powerful magics survive it unprotected? (He won't be unprotected, but just for reference.)
Any additional info would be helpful too.
Actually, 'The Warp' as I generally refer to it isn't the same 'Warp' that exists in Warhammer 40k - that is to say, it's not the home of the Chaos Gods, and isn't affected by the 'real' universe(s) in the slightest (this is because I want to avoid anchoring the cosmology of the Board Battles in any pre-established universe).
The Warp is the polar opposite of the stuff that makes up a 'real' universe, which is why normal matter entering it is typically annihilated almost instantly, and why physics etc are irrelevant there. Normal Universes float within the warp protected by a sort of film or barrier of 'reality', which prevents the Warp from spilling in and destroying that Universe. Although you might want to use the analogy of a bubble, it's not really accurate - that barrier doesn't exist at the 'edges' of a Universe (there's no such thing) - rather, it permeates all of that Universe's existence.
Opening a Warp Gate can occur through a variety of means, and sometimes small Warp Gates even occur spontaneously, since the reality membrane's strength and thickness tends to fluctuate. However, reality abhors these sorts of tears, so they tend to mend themselves extremely quickly.
To open a Warp Gate that is large and stable enough to allow a person to pass through requires something that can breach reality itself - typically this requires a huge expenditure of energy (either magical or technological) that not just bends, but actually rips a hole into time and space. Mortals CAN open Warp Gates - powerful Dark Sorcerers from the Mortal Plane, for example, briefly create Warp Gates when they summon Daemons or cast the Warpstorm spell. Nonetheless, these spells tend to be very exhausting and time consuming to cast (and summoning a Daemon is easier than opening a stable Gate able to accommodate a person).
Surviving the Warp requires the use of Warp Shields, and normal mortals rarely have the skills and endurance required to erect and maintain those. Without them, a mortal's chances of survival in the Warp are zero. If they do manage to erect some Warp Shields, the amount of time they'd need to stay up for simply depends on how 'long' the mortal stays in the Warp - since time, space, and distance is irrelevant there, this could range from as little as a split-second to as long as an eternity. Most regular Warp Travellers have an instinctual sense for the Warp, and can travel to their desired exit (where they must create a second Warp Gate) in a few seconds, but someone without that skill would be throwing their fate completely to chance.
Overusing Warp Shields might lead to them collapsing, so even Warp Travellers tend to avoid using Warp travel if it can be avoided, and they tend not to be able to predict precisely where they will end up either (they tend to get it fairly close, but not on the dot).
Also, note that Warp Shields will protect a person's physical body, but there is still a lot of mental trauma associated with entering the Warp unprepared. That doesn't mean that it's guaranteed to drive you mad, but it's certainly capable of doing so, particularly for someone who hasn't taken careful precautions and learned about the Warp beforehand.