I guess Jasdoif's word of Giant is dogma against magical escapes, but I wonder if Redcloak couldn't have used Hydrogen elementals to gradually blast away at the rock (since they're highly explosive)... a mundane escape utilizing magical components Lirian would assume were unavailable. If the wards prevented such action, what Conradine suggested (bolstering physical strength and simply mining out) might have worked.

Would have taken him longer, and would have cost him the arcane caster (since there was no way on hand to get rid of the virus).

Based on Right Eye's comments (before that word of Giant) I figured that was the implication (and that it ran parallel to Vaarsuvius's temptation). It's not that there weren't other options, it's that Redcloak was blind to them. I might even argue that the audience's interpretation of the situation as a Faustian bargain is more important than the author's original intent. This is also important to note because Redcloak's current characterization (as of the latest comic) demonstrates his propensity to nova, which in some way contradicts what has been said about trying the easy things first.

Spoiler
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Right Eye: "That was three years ago, I'm willing to admit I was wrong"


Might be worth asking the Giant now "Looking back, do you think maybe Redcloak might have been ignoring some of his options in Lirian's prison--like the potential to make explosives from chemical elementals or bolster the digging strength of his men--because he was fixated on 'the plan'?".