changed a quirk to aura and added some info on its inner workings to the book

src/main/java/de/ellpeck/naturesaura/InternalHooks.java

@@ -100,7 +100,7 @@ public class InternalHooks implements NaturesAuraAPI.IInternalHooks {
             }
         });
         BlockPos lowest = lowestSpot.getValue();
-        if (lowest == null)
+        if (lowest == null || lowestAmount.intValue() >= 0)
             lowest = defaultSpot;
         return lowest;
     }
@@ -117,7 +117,7 @@ public class InternalHooks implements NaturesAuraAPI.IInternalHooks {
             }
         });
         BlockPos highest = highestSpot.getValue();
-        if (highest == null)
+        if (highest == null || highestAmount.intValue() <= 0)
             highest = defaultSpot;
         return highest;
     }

src/main/java/de/ellpeck/naturesaura/api/aura/chunk/IAuraChunk.java

@@ -82,7 +82,8 @@ public interface IAuraChunk extends ICapabilityProvider, INBTSerializable<NBTTag
      * This method returns the position of the lowest drain spot (meaning the
      * one that has the least Aura stored) in the given area. This should be
      * used with any machines that fill up Aura in an area, so that the most
-     * drained spots get selected first.
+     * drained spots get selected first. Note that, when there is no drain spot
+     * with an amount lower than 0, the default will always be returned.
      *
      * @param world       The world
      * @param pos         The center position
@@ -99,7 +100,8 @@ public interface IAuraChunk extends ICapabilityProvider, INBTSerializable<NBTTag
      * This method returns the position of the highest drain spot (meaning the
      * one that has the most Aura stored) in the given area. This should be used
      * with any machines that use up Aura so that the spots with the highest
-     * amount are drained first.
+     * amount are drained first. Note that, when there is no drain spot with an
+     * amount greater than 0, the defautl will always be returned.
      *
      * @param world       The world
      * @param pos         The center position

src/main/java/de/ellpeck/naturesaura/chunk/effect/MigrationEffect.java

@@ -28,11 +28,7 @@ public class MigrationEffect implements IDrainSpotEffect {
         if (highestPos == null)
             return;
         IAuraChunk highestChunk = IAuraChunk.getAuraChunk(world, highestPos);
-        MutableInt highestSpot = highestChunk.getDrainSpot(highestPos);
-        if (highestSpot.intValue() <= 0)
-            return;
-
-        int toTransfer = Math.min(25, highestSpot.intValue());
+        int toTransfer = Math.min(25, highestChunk.getDrainSpot(highestPos).intValue());
         highestChunk.drainAura(highestPos, toTransfer);
         auraChunk.storeAura(pos, toTransfer);
     }

src/main/resources/assets/naturesaura/patchouli_books/book/en_us/entries/intro/aura.json

@@ -11,6 +11,14 @@
         {
             "type": "text",
             "text": "However, it isn't always as easy as that. Making use of it wrongly, specifically $(thing)draining$() it completely from an area, will face the culprit with diminishing returns.$(br)So while $(aura) is plentiful and useful, abusing it would certainly be ill-advised.$(p)An additional thing to note is that, based on the world you are in - specifically, the $(item)dimension$(), different types of $(aura) will be present, making some mechanics work unlike expected."
+        },
+        {
+            "type":"text",
+            "text":"When it comes to the inner workings of $(aura), scientists are toubled to admit that they have not quite figured out how exactly it works yet.$(br)The only thing they know is that excess or missing amounts of $(aura) affect an area of varying size (based on the apparatus used) around the place the modification happened from.$(br)If an area is drained and a new generating instrument is added, it will renew the drained area first before creating its own luscious area."
+        },
+        {
+            "type":"text",
+            "text":"Similarly, if a draining instrument is placed close to a rich area, it will first drain that area before moving on to draining the area directly around itself.$(p)While this behavior surely sounds complicated, the consensus is that letting the apparatus and $(aura) do their thing for a while seems to be a good approach of analysis, as sometimes $(aura) tends to migrate and move around to balance itself out naturally."
         }
     ]
 }