Skill RUNES clarification

question
errata
rules

#1

Hello Vikings!

I am playing an L5R Shadowlands hack of VDS and I am using the skills, translated to something more L5R.

One of these skills RUNES (OFUDA in my game) allows the user to:

You have been trained in the mysterious art of drawing mystic geometry to effect.
Roll this skill to scrawl a rune on any surface, with any marking tool. Roll a 4, 5, 6 to do it properly. This symbol will act as a single use spell stone when activated. You determine activation conditions and what spell stone is used.

That last part is what confuses my player and myself as the GM. Do you all play it as:

  • Player determines activation conditions AND whatever spell effect they choose

OR

  • Player determines activation conditions AND what spell stone is used from the list of spell stones they already have?

OR

  • Player determines conditions and what spell EFFECT they would like (kinda like free form casting)

Any help would be appreciated!