diff --git a/common/script/content/spells.js b/common/script/content/spells.js
index 9a58e85394..7609bd844a 100644
--- a/common/script/content/spells.js
+++ b/common/script/content/spells.js
@@ -218,10 +218,10 @@ spells.healer = {
     text: t('spellHealerBrightnessText'),
     mana: 15,
     lvl: 12,
-    target: 'self',
+    target: 'tasks',
     notes: t('spellHealerBrightnessNotes'),
-    cast (user) {
-      _.each(user.tasks, (task) => {
+    cast (user, tasks) {
+      _.each(tasks, (task) => {
         if (task.type !== 'reward') {
           task.value += 4 * (user._statsComputed.int / (user._statsComputed.int + 40));
         }
diff --git a/website/src/controllers/api-v3/user.js b/website/src/controllers/api-v3/user.js
index 39efc002f9..bcdad4d9f1 100644
--- a/website/src/controllers/api-v3/user.js
+++ b/website/src/controllers/api-v3/user.js
@@ -1,6 +1,15 @@
 import { authWithHeaders } from '../../middlewares/api-v3/auth';
 import cron from '../../middlewares/api-v3/cron';
 import common from '../../../../common';
+import {
+  NotFound,
+  BadRequest,
+} from '../../libs/api-v3/errors';
+import * as Tasks from '../../models/task';
+import { model as Group } from '../../models/group';
+import { model as User } from '../../models/user';
+import Q from 'q';
+import _ from 'lodash';
 
 let api = {};
 
@@ -31,4 +40,117 @@ api.getUser = {
   },
 };
 
+const partyMembersFields = 'profile.name stats achievements items.special';
+
+/**
+ * @api {post} /user/class/cast/:spell Cast a spell on a target.
+ * @apiVersion 3.0.0
+ * @apiName UserCast
+ * @apiGroup User
+ *
+ * @apiParam {string} spellId The spell to cast.
+ * @apiParam {UUID} targetId Optional query parameter, the id of the target when casting a spell on a party member or a task.
+ *
+ * @apiSuccess {Object|Array} mixed Will return the modified targets. For party members only the necessary fields will be populated.
+ */
+api.castSpell = {
+  method: 'POST',
+  middlewares: [authWithHeaders(), cron],
+  url: '/user/class/cast/:spell',
+  async handler (req, res) {
+    let user = res.locals.user;
+    let spellId = req.params.spellId;
+    let targetId = req.query.targetId;
+
+    // optional because not required by all targetTypes, presence is checked later if necessary
+    req.checkQuery('targetId', res.t('targetIdUUID')).optional().isUUID();
+
+    let reqValidationErrors = req.validationErrors();
+    if (reqValidationErrors) throw reqValidationErrors;
+
+    let klass = common.content.spells.special[spellId] ? 'special' : user.stats.class;
+    let spell = common.content.spells[klass][spellId];
+
+    if (!spell) throw new NotFound(res.t('spellNotFound', {spell: spellId}));
+    if (spell.mana > user.stats.mp) throw new BadRequest(res.t('notEnoughMana'));
+    let targetType = spell.target;
+
+    if (targetType === 'task') {
+      if (!targetId) throw new BadRequest(res.t('targetIdUUID'));
+
+      // TODO what about challenge tasks? should casting be disabled on them?
+      let task = await Tasks.Task.findOne({
+        _id: targetId,
+        userId: user._id,
+      }).exec();
+      if (!task) throw new NotFound(res.t('taskNotFound'));
+      if (task.challenge.id) throw new BadRequest(res.t('challengeTasksNoCast'));
+
+      spell.cast(user, task);
+      await task.save();
+      res.respond(200, task);
+    } else if (targetType === 'self') {
+      spell.cast(user);
+      await user.save();
+      res.respond(200, user);
+    } else if (targetType === 'tasks') { // new target type when all the user's tasks are necessary
+      let tasks = await Tasks.Task.find({
+        userId: user._id,
+        'challenge.id': {$exists: false}, // exclude challenge tasks
+        $or: [ // Exclude completed todos
+          {type: 'todo', completed: false},
+          {type: {$in: ['habit', 'daily', 'reward']}},
+        ],
+      }).exec();
+
+      spell.cast(user, tasks);
+
+      let toSave = tasks.filter(t => t.isModified());
+      let isUserModified = user.isModified();
+      toSave.unshift(user.save());
+      let saved = await Q.all(toSave);
+
+      let response = {
+        tasks: isUserModified ? _.rest(saved) : saved,
+      };
+      if (isUserModified) res.user = user;
+      res.respond(200, response);
+    } else if (targetType === 'party' || targetType === 'user') {
+      let party = await Group.getGroup({_id: 'party', user});
+
+      // arrays of users when targetType is 'party' otherwise single users
+      let partyMembers;
+
+      if (targetType === 'party') {
+        if (!party) {
+          partyMembers = [user]; // Act as solo party
+        } else {
+          partyMembers = await User.find({'party._id': party._id}).select(partyMembersFields).exec();
+        }
+
+        spell.cast(user, partyMembers);
+        await Q.all(partyMembers.map(m => m.save()));
+      } else {
+        if (!party && (!targetId || user._id === targetId)) {
+          partyMembers = user;
+        } else {
+          if (!targetId) throw new BadRequest(res.t('targetIdUUID'));
+          partyMembers = await User.findOne({_id: targetId, 'party._id': party._id}).select(partyMembersFields).exec();
+        }
+
+        if (!partyMembers) throw new NotFound(res.t('userWithIDNotFound', {userId: targetId}));
+        spell.cast(user, partyMembers);
+        await partyMembers.save();
+      }
+      res.respond(200, partyMembers);
+
+      if (party && !spell.silent) {
+        let message = `\`${user.profile.name} casts ${spell.text()}${targetType === 'user' ? ` on ${partyMembers.profile.name}` : ' for the party'}.\``;
+        party.sendChat(message);
+        await party.save();
+      }
+    }
+  },
+};
+
 export default api;