While designing an adventure, I needed my players to have an excuse to cast 'detect Poison' on several items. Knowing that the spell is a little expensive, I felt that plausibly something could be done, sure, I could make it more obvious, by giving them a scroll or two, or have someone teach the spell to a mage in the party, but even then it needs to be used more often.
And I asked myself.. What is Detect Poison? What is Detect Magic?
What is detection magic:
Consider first, how does it work. Is the magic sending out sound waves, when it hits the target object, it detects 'waves' of magic, and sends back to the caster some feedback his/her brain interprets as an Aura, and lets them know, YES this is magical?
Is it then, that they take that skill, and further it, identifying the particular waves to determine what KIND of magic it is?
What about the other direction, if they reduced its ability, and lessened the cost. could the spell merely detect 'something'?
Side Note: Would Detect Magic, detect Radiation? would a caster assume its 'magic' but of unknown variant, and take it home, expecting to find out from a more powerful mage, and slowly become sick?
Would it make more sense, that the early mage, in learning the spell, would have gone through the weaker version? 'detect something'?
In which case, would it make far more sense that a "detect" Spell be learnt far earlier? and that spell likely improved on also.
I'd like to think, given that magical items are rare, that its far more cost effective for a mage to learn to cast 'detect' far in advance of 'detect magic/poison/undead/evil'
I give you the Detection Spells:
Possible components: glass prism/lens/obj smaller than 4cm - consumed 50% reduction.
Range: Touch
Initiative: 1 Round.
Caster concentrates and absorbs the sense of the object, If the Object is imbued with any effect, or is of pure metal, it will give a positive feeling to the casters hand.
Base Cost: 5mp [-10%mp*]
Possible components: glass prism/lens/obj smaller than 4cm - consumed 50% reduction. [+10%]
Additional components: 5% gestures, +5% somantic CR
Range: Touch [+1/2m]
Effect: [directional focus: 180o 120o 90o 75o, etc]
Multiple senses: [+1]
Initiative: [Half Round, Action, Half Action, Free Action]
As Above, the Enhanced spell can be improved to detect objects at a distance, using the component to search in a direction or a whole room. A Caster could in effect search a room for 'any' effected item, and sense the direction of the items.
Example: Search Room, lvl 4
Base Cost: 17mp. & 20% imperfection. Final Cost 2mp.
Components: glass lens [-8mp], 4 small candles[-3mp], small rug[-1mp] and humming the incantus majori[-3mp].
Range: 5 x 5m room
Caster seated on the small rug, a lit candle in each cardinal direction, peering with one eye through the monocle, and humming the incantus majori, concentrates for 3 rounds and absorbs the sense of the room. If any item of importance exists in the room, the candle nearest will glow, giving the caster (and anyone watching) the direction of the most powerful object in the room.
Quick Detect lvl 1
Base Cost: 2mp, & 3% imperfection. Final Cost 1mp.
Components: glass/crystal object [-1mp].
Range: Touch
With a small quarts crystal in hand, The caster quickly detects the item in the same hand, is effected of some force. Most magi would take their detect spell to this level with only 3 restudies.
But if they want to take it further:
Free and Easy Detect: lvl 6.
Base Cost: 0mp, & 30% imperfection.
Range: 1.5m, no line of sight
As a Free Action, The Mage is able to hold their hand within a metre and a half of an object and detect if it may have an effect. This is a more likely end point to such a spell, taking it further to search rooms comes at such cost to negate the effectiveness without serious levels of study.
Conclusion of Detect Magic
As you can see, having some improved level of magic detection, which is inexpensive, is far more effective than attempting to cast 'detect magic' on every single item. The cost of studying 'free and easy detect' might seem worth it, yet, given a mage has limited study time between adventures, the player has to determine if indeed this is worthwhile, and is maybe influenced by how often you include small to mundane magical items in your campaigns.
So What of detect Poison? Undead? Evil? or just plain 'pure' metal?
In theory, they should have some kind of similarity, yet we have a few modifiers.
Undead and or Evil, might have tell tale signs before the mage/priest/monk even attempts the ability to detect, and the detection merely confirms what they suspect. Where for example a mage might look at a glowing stone, and assume its magical, so the exertion to determine is quickly ascertained as a yes, should mean some kind of feedback cost reduction.
i.e. if the meta-physics is that mid expenditure of power, you confirm what you already expect, you can cancel the spell before it comes to completion. So then we need to add to the above spells, casting on already obviously magical items can have a -1 cost to cast. This allows GMs some good story telling arcs and plot paths, where maybe the item is glowing from paint, small bugs or some other bioluminescence, and the players just assume its magical. The Mage casts 'detect' and gets nothing, either assuming he failed the roll, or that the item has counter magic on it, to prevent detection. So they need to track down a better mage to properly counter the magic. Along the way they can meet other people for other plot paths.