Summon something from there

The spell "Summon something from there" lets the spellcaster summon up an entity by pointing with her index finger at something, while uttering the spell's name.

A thin ray, magenta in colour, shoots out from the finger, tracing a perfectly straight line from the finger to whatever it hits first, and what it hits, is what the summoned entity will be entirely based on.

All the pointy-hat attendees at the Great Sorcerous World Faire of the year 148 thought this new spell was the most exciting thing ever, so much in fact that they named it and its inventor Caster and Spell of the Year (it had been a rather bland and dull year, to be honest). All the faire participants clapped their hands and smiled with their wine-soaked lips and teeth, and agreed that this truly was very exciting times to be alive, Gods bless us, everybody!

However, real wizards and sorcerers, i.e. grumpy bastards living in towers as crooked as themselves, pointed out two crucial facts:

1. The caster doesn't know which index finger will be used by the ray; thus was the Boot Imp born
2. The entity is merely based on the object the ray hits; e.g. the caster wanted a iron demon but got a fork variety instead
   

So, after some heated discussions, most real wizards started calling users of the spell for Can't-Be-Arsed-Wizards since they didn't seem to care about what they were actually summoning, and moved on with their lives (that is, locked the front door and continued being grumpy in solitude).

That said, it still was a fairly popular spell for a couple of years, until it reached a turning point in the year 173 when the (up to that point) great wizard Salphourza the Askewed had promised her king that no army was needed to fight off the invading forces that were approaching the castle; the great wizard and her trusty finger would save the kingdom! She bravely walked out on her own to meet the invaders on the field outside the castle, and with a firm voice she cried out: "YOU'VE TRAVELLED FAR, BAZGHUR THE BALD, BUT HERE YOUR JOURNEY ENDS. TURN BACK, OR FACE THE UNBELIEVABLE COSMIC HORROR FROM THE FARTHEST AND COLDEST REACHES OF THE DARK AND DEAD STARS!"

She then pointed her index finger in an overly dramatic posture straight up into the sky, uttered the spell name as loud as she could, and watched the magenta ray shoot out from her finger in a straight line into the sky; further...and further...and further...and further... The ray seemed to never end.

After a while Bazghur the Bald and his invading army grew tired of waiting, so they just rode past the wizard and took the city quite easily, leaving the poor wizard seemingly stuck in place, because that was the third crucial fact about the spell that real wizards had discovered; the caster can't move as long as the ray is out.