Example A. Merlin is an immortal who appears in the world as an old wizard, and he is trying to take control of King Arthur (a pre-defined Hero) and the Fortress Camelot (an also already existing Creation). Imagine that this chapter appears somewhere in the middle of a longer story, so there is some stuff going on before and after.
Some days later, Merlin stepped into the courtyard again and was met by King Arthur, who longed for his wisdom. They discussed the enemy forces gathered outside the fortress and how to defeat them (optional: write direct speech dialog, if you wish). The King listened closely to Merlins advise, and then proceeded to follow it [Effect: Gain Influence +3 / Cost: 9 Prime].
The next morning, there was commotion among the tents of the besieging army, just as the sun rose. Soon, it turned into panic and shouts were heard all over the camp. From the ramparts, soldiers could be seen running around half-naked, or stabbing the ground with their weapons. Some ran into the forest, never to be seen again. Some ran closer to the fortress and were picked off by archers. When the sun came over the horizon completely, the panic slowly subsided. The illusionary snakes did not stand up to the full sunlight, but they had done what they were supposed to do and considerably weakened the enemy. Merlin was happy with himself [Effect: Magic / Cost: 1 Prime -- Note: The attacking army in this story is not a creation fueled by Prime, so the only cost here is for using magic. If the army were a creation, say by another Immortal, then weakening it would have to be played as an effect of changing the army, adding a "weakened" or "demoralised" attribute to it. But since the army only exists as background to the story, it can be freely manipulated].