This is a common problem I have writing fantasy. Most of the trouble comes from revealing a monster, but for the characters who have never seen the monster before, they don't know what it is. One example is a minotaur, to describe it as a minotaur lets the reader know what it is straight away, the problem is if i write 'minotaur', a following scene with a character discovering it's a minotaur becomes redundant, and though there are monsters I have a character introduce before their encounter, this seems convenient after a while. It takes away the drama, and after a while writing ' a bull with legs' gets repetitive. Any tips, rule of thumb? Cheers.
Maybe the viewpoint character could refer to the minotaur as 'the beast' or 'the monster'? Meanwhile, you could indicate to the readers that it is a minotaur by describing its appearance in such a way that it is fairly obvious. For example, you could say something like: I spun around to see a hulking beast standing behind me. The monster had the head of a bull, but when it opened its mouth I could see sharp, blood-covered teeth inside. Though it stood on two legs and had arms like a human, it was covered in shaggy brown fur and had hooves instead of feet. The beast growled, then charged, thrusting forward wickedly sharp horns.
Just an idea. You may want to look at a few Rick Riordan books; he does an excellent job of describing mythological creatures.
Well, this is something that I have a bit of experience in, being the GM of a fantasy RPG, Pathfinder. It's all about player (or reader) and character knowledge. For example, I may give my players an enchanted sword, but I might give it to them like this.
"You pry the blade out of the beasts' hands, with the blood of your fallen comrade still fresh on it. As you grip it, you feel a slight rush of power flow from it to you."
It's only a +1 blade, but I made it seem like it was a very powerful artifact (Which, at level 1-5, was not at all happening.)
Regardless, back to your question, here's a few options.
First off, you don't. You don't have to introduce the monster. Sometimes, it's more impactful not to, particularly if it's an extremely powerful creature at that stage (Think, facing a minotaur at 1st level. I've only had one party survive, only due to some divine (GM) intervention.)
Second, you could do as the person above me said, and describe in detail the monster or enemy they are facing. This gives a sense of suspense as the characters and the readers realize "Oh, s***, it's a minotaur! Run!"
Third, if at all possible, vaguely describe the monster. This is particularly effective for undead and other similar enemies. I've once disguised a succubus as an innocent farm girl, only to have one of the characters unlock the secret with the victim's body inside. They hated me for that, but I had a wicked laugh. Sometimes, it pays to be evil.
Hope that was useful!
The answer to this depends on your narrative point of view. If you are writing 1st person, or 3rd person close, you want the reader to experience the world as the character does. So you don't want to describe the monster in ways that the character wouldn't have access to, because it would move the reader out of the character's head. On the other hand, if you're writing 3rd person omniscient, you'll most often describe the monster directly to the readers in terms they'll understand.
The key here is understanding what function your descriptions are serving. For close perspective, the objective is to make the reader identify with the character's experience. Using terms like "minotaur" will not help with that goal (unless minotaurs are something the character actually is familiar with). But if the perspective is omniscient, you're trying to give the reader the big picture perspective, watching from the outside.
If you're trying to give the inside view, and it's getting clunky and awkward, or repetitive, consider that might just be a symptom of a deeper problem. Maybe you don't need to give a play-by-play of every battle after all. If it's not interesting to describe it from the character's point of view, maybe you just need to skip over it.