Scrying, with its higher level counterparts, is the most powerful spell in the books. People talk about the versatility that makes the wizard so good, but it's good preparation that makes him able to use that versatile spell list. And what helps you know what you're up against? Scrying. Why are BBEG's so mean and evil? Because they have lower level mook wizards scrying on the party all the time so the BBEG knows exactly what they're up to.
That being said, because Scrying is the single most powerful line of spell in the game, Detect Scrying then becomes the 4th level defense for it. If focused on you, or someone in the group, the scrying sensor will appear within the 40' range. And you have a shot at seeing the offender... to possibly set up your own scrying attempt.
And for completely different reasons, Polymorph is for the wizard who wants to not be in melee anymore. It is the APC of wizard spells... the umberhulk shows up and burrows 20' striaght down without a tunnel behind him. Need a place to rest? Carve out a burrow beneath the earth with an air hole. Better than Rope Trick.
That being said, because Scrying is the single most powerful line of spell in the game, Detect Scrying then becomes the 4th level defense for it. If focused on you, or someone in the group, the scrying sensor will appear within the 40' range. And you have a shot at seeing the offender... to possibly set up your own scrying attempt.
And for completely different reasons, Polymorph is for the wizard who wants to not be in melee anymore. It is the APC of wizard spells... the umberhulk shows up and burrows 20' striaght down without a tunnel behind him. Need a place to rest? Carve out a burrow beneath the earth with an air hole. Better than Rope Trick.