Syntax is MEDITATE RUNESTONE <command>

Any of these may result in an inner fire gain, loss or neither. It has been implied that not meeting certain strength levels may increase the chances of inner fire loss. In addition, often the runestone explosion will slightly injure you, but only on the ones involving bare flesh (which are starred in the lists below).

Options and Results

Note: The crush messaging you receive appears to be random.

MEDITATE <runestone> CRUSH
You scowl at a <runestone> and toss it over your shoulder, lost forever.

MEDITATE <runestone> CRUSH*
You close your fingers about the <runestone> as you fuel your grip with your inner strength. Your knuckles crack as you squeeze tighter and tighter, just when you think you can squeeze no more, you feel the runestone begin to give. Clenching your teeth you tighten your fist even more, forcing the runestone to finally crumble beneath your strength with a satisfying ***POP***. As you open your hand, the dust that remains drifts away, leaving nothing behind.

MEDITATE <runestone> CRUSH*
Smirking, you center your inner fire on a <runestone> and bring your palms together around it. Slowly, you push your palms together, enjoying the groans and squeeks of the <runestone> as it tries to resist your strength. Suddenly, the runestone gives way to the pressure of your palms, with a brillant flash of light nothing but sparkling dust is left on your hands. You casually rub the remains from your hands.

MEDITATE <runestone> BASH <without blunt weapon>]*
For a moment you stare at the <runestone> that lies helpless in your hand. Then, summoning your inner strength, you drive your other fist into the runestone, pulverizing it into fine dust. You cannot help a slight smile as you grind your knuckles into your palm to remove the remaining dust.

MEDITATE <runestone> BASH <with blunt weapon>
You spread your arms wide and clench your grip on your <weapon> before slamming the head of your <weapon> into your palm, crushing the helpless <runestone> into a fine sparkling dust.

MEDITATE <runestone> SMASH*
A smile crosses your face as you gaze at the runestone. In a display of speed and strength that would make Everild proud, you smash the runestone against your forehead. A blinding flash of light followed by a small explosion catches you slightly off-guard as the runestone erupts in a final display of futile magic.

MEDITATE <runestone> EAT
You center your inner strength and will as you glare at the <runestone> in your hand. Inspiration strikes, and you pop the runestone into your mouth and crush it between your back teeth. You spit out a slurry of saliva and sparkling dust -- all that remains of the runestone -- with disdain.

MEDITATE <runestone> SLAM*
Centering your inner strength and will on the <runestone>, you toss it up and catch it in the crook of your arm. With a roar you flex your biceps, pulling your fist to your chest and crushing the <runestone> with a loud ***POP***. A fine sparkly powder drifts away into the air as you relax your arm.

MEDITATE <runestone> ASSAULT <with blunt weapon>
Taking one last glance at the thing you hold that some call a runestone, you toss it high overhead as you center your mind on your inner strength. With a high overhead strike your <weapon> smashes into the falling <runestone>, and with a small but satisfying explosion, the dust of the pulverized runestone drifts away into the air.

MEDITATE <runestone> ASSAULT <with edged weapon>
Taking one last glance at the thing you hold that some call a runestone, you toss it high overhead as you center your mind on your inner strength. With a brutal mid-chest lunge, your <weapon> smashes into the falling <runestone>, lodging it on your <weapon>. Grumbling you pull the runestone from your <weapon> and toss it aside.

MEDITATE <runestone> ASSAULT <with halberd or quarterstaff>
Taking one last glance at the thing you hold that some call a runestone, you toss it high overhead as you center your mind on your inner strength. With a brutal mid-chest swing, your <weapon> smashes into the falling <runestone>, launching it upward. You strain the see the runestone as it shrinks into nothingness and is lost.

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Thanks to Caraamon for gathering and organizing the above information.