I guess you intend Rune Blade, right?
You roll 4 dice (regardless of the attack type and whatevs, like modifiers and so on). Then:
a) you must place at least one die on the lore card, preserving the result(s)
b) if any of the dice are still not on the card, you roll the remaining ones and repeat a) until your pool of "free dice" is reduced to zero
After all dice are placed on the card, you resolve them as if this was your combat roll
Lemme know if it has sense or you have further questions, always happy to help