Detect Magic Spell
Detect Magic Description: You detect magical auras. The amount of information revealed depends on how long you study a particular area or subject.
1st Round: Presence or absence of magical auras.
2nd Round: Number of different magical auras and the power of the most potent aura.
More: D&D Spells for Detect Magic
Really cannot see a magician walking into the mage's dungeon not having a basic spell like this. Picture: Someone asks the party's magician if he knows if a certain area has magic, he replies, "Sorry I am a magic-user but cannot tell if magic is there...".
I prefer to just make 'Detect Magic' a function of skills. Perception to notice the 'presence' magic, normally by none visual cues. I tend to run it as tactile. The feel of magic makes your hairs stand on end like static. Then Knowledge Arcana or Spellcraft to really analyze the aura to know more about it.
The spell 'Detect Magic' streamlines that analysis, making it much quicker and easier.
Making the detection of magic the sole province of that spell, makes it just seems like a spell tax. Not taking the spell is sort of ludicrous in those sorts of situations.