A simple and completely untested variant system for casting spells in Lamentations of the Flame Princess. It should also work with other OSR games, but LotFP allows mages to wear armor and use weapons, which makes a severe toning down of spellcasting much less disruptive for players.
Spells work pretty much the same way under this system except that you don’t need to prepare spells in advance and all casting times are at least 1 minute (10 rounds) long. You still need to have spell slots available which are used up for the day when a spell is cast. The effect is that spellcasters become much more flexible in picking their spells when the situation comes up but at the same time lose the ability to quickly intervene with spells in the middle of a fight. All magic requires at least a bit of time to prepare during which the spellcaster can easily be interrupted by any hostile creatures or violent environment conditions.
Many spells need to be cast from hiding, either in cover or in plain sight, to be of any use. I think that I would rule that it’s sufficient for a spellcaster to stand or sit and do nothing and quietly recite the magical incantations at low volume. It would be easy to spot by people who are standing close enough to the caster to hear the magic words or who are keeping an eye on him. Loud background noise or some kind of distraction would be necessary to cast a spell unnoticed while in a crowd. The changes also make a good number of spells effectively useless. The following spells I’d remove from the game. (Fireball and lightning bolt are already not part of the LotFP rules.)
- Heat Metal
- Protection from Evil
- Protection from Evil, 10′ Radius
- Remove Fear
- Army of One
- Death Spell
- Faithful Hound (if the duration is indeed correct)
- Feather Fall
- Globe of Invulnerability (Greater and Lesser)
- Grasping Hand
- Hold Person/Monster
- Interposing Hand
- Magic Missile
- Magic Sword
- Mirror Image
- Mnemonic Enhancer
- Power Word Kill
- Power Word Stun
- Prismatic Spray
- Ray of Enfeeblement
- Spell Turning
- Witchlamp Aura
- Charm Person/Monster: The target makes a saving throw at the start of the casting of the spell. If it fails it will simply listen to the casters words and not take any action unless the casting is interrupted by an outside source. The caster of the spell does not look like he is casting a spell on the target but has to keep talking for the entire casting time and observers might notice something strange going on with the target.
- Enthrall: The crowd starts listening to the caster immediately but can only be persuaded to do something after at least a minute of talking to them has passed.
- Polymorph Others: The target of the spell slowly begins to change during the casting time but reverts to its original form if the spell is interrupted in any way.
- Sacrifice: The caster has to be in contact for the entire casting time of the spell, usually making it necessary to restrain the target.
- Suggestion: The target makes a saving throw at the start of the casting of the spell. If it fails it will simply listen to the casters words and not take any action unless the casting is interrupted by an outside source. The caster of the spell does not look like he is casting a spell on the target but has to keep talking for the entire casting time and observers might notice something strange going on with the target.