diff --git a/disco/bot/command.py b/disco/bot/command.py
index 08c9b9f..1cf00a1 100644
--- a/disco/bot/command.py
+++ b/disco/bot/command.py
@@ -7,7 +7,10 @@ from disco.util.functional import cached_property
 
 REGEX_FMT = '({})'
 ARGS_REGEX = '( ((?:\n|.)*)$|$)'
-MENTION_RE = re.compile('<@!?([0-9]+)>')
+
+USER_MENTION_RE = re.compile('<@!?([0-9]+)>')
+ROLE_MENTION_RE = re.compile('<@&([0-9]+)>')
+CHANNEL_MENTION_RE = re.compile('<#([0-9]+)>')
 
 CommandLevels = Enum(
     DEFAULT=0,
@@ -145,10 +148,13 @@ class Command(object):
             else:
                 return ctx.msg.mentions.select_one(username=uid[0], discriminator=uid[1])
 
+        def resolve_channel(ctx, cid):
+            return ctx.msg.guild.channels.get(cid)
+
         self.args = ArgumentSet.from_string(args or '', {
-            'mention': self.mention_type([resolve_role, resolve_user]),
-            'user': self.mention_type([resolve_user], force=True, user=True),
-            'role': self.mention_type([resolve_role], force=True),
+            'user': self.mention_type([resolve_user], USER_MENTION_RE, user=True),
+            'role': self.mention_type([resolve_role], ROLE_MENTION_RE),
+            'channel': self.mention_type([resolve_channel], CHANNEL_MENTION_RE),
         })
 
         self.level = level
@@ -159,7 +165,7 @@ class Command(object):
         self.dispatch_func = dispatch_func
 
     @staticmethod
-    def mention_type(getters, force=False, user=False):
+    def mention_type(getters, reg, user=False):
         def _f(ctx, raw):
             if raw.isdigit():
                 resolved = int(raw)
@@ -167,7 +173,7 @@ class Command(object):
                 username, discrim = raw.split('#')
                 resolved = (username, int(discrim))
             else:
-                res = MENTION_RE.match(raw)
+                res = reg.match(raw)
                 if not res:
                     raise TypeError('Invalid mention: {}'.format(raw))
 
@@ -178,10 +184,7 @@ class Command(object):
                 if obj:
                     return obj
 
-            if force:
-                raise TypeError('Cannot resolve mention: {}'.format(raw))
-
-            return resolved
+            raise TypeError('Cannot resolve mention: {}'.format(raw))
         return _f
 
     @cached_property
diff --git a/disco/types/base.py b/disco/types/base.py
index 56657ff..dfa1e2c 100644
--- a/disco/types/base.py
+++ b/disco/types/base.py
@@ -73,6 +73,7 @@ class Field(object):
         try:
             return self.deserializer(raw, client)
         except Exception as e:
+            raise
             six.reraise(ConversionError, ConversionError(self, raw, e))
 
     @staticmethod
@@ -281,11 +282,11 @@ class Model(six.with_metaclass(ModelMeta, AsyncChainable)):
         self.load(obj)
 
     @property
-    def fields(self):
+    def _fields(self):
         return self.__class__._fields
 
     def load(self, obj, consume=False, skip=None):
-        for name, field in six.iteritems(self.fields):
+        for name, field in six.iteritems(self._fields):
             should_skip = skip and name in skip
 
             if consume and not should_skip:
@@ -305,7 +306,7 @@ class Model(six.with_metaclass(ModelMeta, AsyncChainable)):
             setattr(self, field.dst_name, value)
 
     def update(self, other):
-        for name in six.iterkeys(self.fields):
+        for name in six.iterkeys(self._fields):
             if hasattr(other, name) and not getattr(other, name) is UNSET:
                 setattr(self, name, getattr(other, name))