Powerful Toys

Because all of the magic in my world is of my own creation (I used a modified version of the Cleric spell list), I frequently encounter situations where my players use magic in a completely new way that catches me by surprise and can obviate the challenges in front of them.  While this can and does happen with all magic systems, the two the party favors (rituals and sorcery) lend themselves well to creative interpretations.

Rituals are magical ceremonies that enact a temporary physical change in an object.  My Saturday players primarily use rituals to enchant wands, which everyone can use.  Each ritual requires a consumable component (shard fragments) which are expensive, but the party has amassed a rather significant collection of them and feels free to perform all the rituals they want.  One of the wands they really enjoy using is a wand of lightning.  It creates a version of the default Lightning Bolt spell found in most D&D games - straight line of energy dealing 5d6 damage to whatever it passes through, with a length of perhaps 40 yards.  Against a formidable opponent, the party armed each member with such a wand and blasted it to smithereens in two rounds (admittedly, on the beast's turn, it killed two characters and almost killed a third).  The fight was much briefer than I anticipated.

Now, the question comes to me: how do I present a challenge to a party with this power?  I know a great many DMs who would respond by presenting the party with enemies resistant or immune to the effect, making it useless.  I know others who might weaken the spell.  The problem with both strategies is that it creates an arms race between players and DM.  The question itself places the DM and players in competition with each other.

A better question is "how do I respond to the party having this power?"  Except the answer to this question is to do nothing different.  'You' mustn't respond, you must run the world in exactly the same fashion as before - to do otherwise is to compromise the world for the sake of you, the DM, feeling like you have 'challenged' the party.  It's an ego trip.  You can do better.

And here lies the tricky bit.  Your world will respond.  Running your world the same way doesn't mean your players will find the same encounters, fight the same foes.  My players have demonstrated, rather frequently, that they have access to a lot of wands of lightning.  So their enemies won't line up obediently to be slaughtered.  They will use their own wands of lightning.  They will respond to the players' tactics with tactics of their own.

And this works well for enemies that know the party's skillset and tactics.  But the rest of  the world?  They will be blindsided.