diff --git a/plugin/src/main/java/lol/pyr/znpcsplus/entity/EntityPropertyRegistryImpl.java b/plugin/src/main/java/lol/pyr/znpcsplus/entity/EntityPropertyRegistryImpl.java
index c3906cf..08ede74 100644
--- a/plugin/src/main/java/lol/pyr/znpcsplus/entity/EntityPropertyRegistryImpl.java
+++ b/plugin/src/main/java/lol/pyr/znpcsplus/entity/EntityPropertyRegistryImpl.java
@@ -102,14 +102,6 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
         // Guardian
         registerType("is_elder", false); // TODO: ensure it only works till 1.10. Note: index is wrong on wiki.vg
 
-        // Shulker
-        registerType("attach_direction", null); // TODO: make a direction enum
-        registerType("shield_height", 0); // TODO: figure this out
-        registerType("shulker_color", DyeColor.RED); // TODO
-
-        // Wither
-        registerType("invulnerable_time", 0); // TODO
-
          */
     }
 
@@ -366,6 +358,17 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
             linkProperties("wolf_angry", "tamed", "sitting");
         }
 
+        // Wither
+        int witherIndex;
+        if (ver.isNewerThanOrEquals(ServerVersion.V_1_17)) witherIndex = 16; // using the first index, so we can add the other properties later if needed
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_15)) witherIndex = 15;
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_14)) witherIndex = 14;
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_10)) witherIndex = 12;
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_9)) witherIndex = 11;
+        else witherIndex = 17;
+        witherIndex += 3; // skip the first 3 indexes, will be used for the other properties later
+        register(new IntegerProperty("invulnerable_time", witherIndex++, 0, false));
+
         if (!ver.isNewerThanOrEquals(ServerVersion.V_1_9)) return;
         // Shulker
         int shulkerIndex;
diff --git a/plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeRegistryImpl.java b/plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeRegistryImpl.java
index 3780ed0..4a8f77b 100644
--- a/plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeRegistryImpl.java
+++ b/plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeRegistryImpl.java
@@ -153,7 +153,8 @@ public class NpcTypeRegistryImpl implements NpcTypeRegistry {
                 .addProperties("hand"));
 
         register(builder(p, "wither", EntityTypes.WITHER)
-                .setHologramOffset(1.525));
+                .setHologramOffset(1.525)
+                .addProperties("invulnerable_time"));
 
         register(builder(p, "wolf", EntityTypes.WOLF)
                 .setHologramOffset(-1.125)