diff --git a/phpBB/config/default/container/services_twig.yml b/phpBB/config/default/container/services_twig.yml
index ce76a6a5ea..f3ad95207d 100644
--- a/phpBB/config/default/container/services_twig.yml
+++ b/phpBB/config/default/container/services_twig.yml
@@ -43,6 +43,25 @@ services:
         tags:
             - { name: twig.extension }
 
+    template.twig.extensions.auth:
+        class: phpbb\template\twig\extension\auth
+        arguments:
+            - '@auth'
+        tags:
+            - { name: twig.extension }
+
+    template.twig.extensions.avatar:
+        class: phpbb\template\twig\extension\avatar
+        tags:
+            - { name: twig.extension }
+
+    template.twig.extensions.config:
+        class: phpbb\template\twig\extension\config
+        arguments:
+            - '@config'
+        tags:
+            - { name: twig.extension }
+
     template.twig.extensions.routing:
         class: phpbb\template\twig\extension\routing
         arguments:
@@ -50,6 +69,11 @@ services:
         tags:
             - { name: twig.extension }
 
+    template.twig.extensions.username:
+        class: phpbb\template\twig\extension\username
+        tags:
+            - { name: twig.extension }
+
     template.twig.extensions.debug:
         class: Twig_Extension_Debug
 
diff --git a/phpBB/phpbb/template/twig/extension/auth.php b/phpBB/phpbb/template/twig/extension/auth.php
new file mode 100644
index 0000000000..83a626e523
--- /dev/null
+++ b/phpBB/phpbb/template/twig/extension/auth.php
@@ -0,0 +1,91 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\template\twig\extension;
+
+class auth extends \Twig_Extension
+{
+	/** @var \phpbb\auth\auth */
+	protected $auth;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param \phpbb\auth\auth	$auth	Authentication object
+	 */
+	public function __construct(\phpbb\auth\auth $auth)
+	{
+		$this->auth = $auth;
+	}
+
+	/**
+	 * Get the name of this extension
+	 *
+	 * @return string
+	 */
+	public function getName()
+	{
+		return 'auth';
+	}
+
+	/**
+	 * Returns a list of global functions to add to the existing list.
+	 *
+	 * @return array An array of global functions
+	 */
+	public function getFunctions()
+	{
+		return array(
+			new \Twig_SimpleFunction('auth', array($this, 'get_auth')),
+			new \Twig_SimpleFunction('auth_global', array($this, 'get_auth_global')),
+		);
+	}
+
+	/**
+	 * Look up permission option(s).
+	 *
+	 * How to use in a template:
+	 * - {{ auth(options, forum_id) }}
+	 *
+	 * The options are required, either as a single string 'a_' or as a twig array ['a_', 'm_'].
+	 * The forum identifier is optional.
+	 *
+	 * @return bool
+	 */
+	public function get_auth()
+	{
+		$args = func_get_args();
+
+		$options = $args[0];
+		$forum_id = isset($args[1]) ? (int) $args[1] : 0;
+
+		return is_array($options) ? $this->auth->acl_gets($options, $forum_id) : $this->auth->acl_get($options, $forum_id);
+	}
+
+	/**
+	 * Look up permission option(s) for any forum
+	 *
+	 * How to use in a template:
+	 * - {{ auth_global(options) }}
+	 *
+	 * The options are required, either as a single string 'a_' or as a twig array ['a_', 'm_'].
+	 *
+	 * @return bool
+	 */
+	public function get_auth_global()
+	{
+		$args = func_get_args();
+
+		return $this->auth->acl_getf_global($args);
+	}
+}
diff --git a/phpBB/phpbb/template/twig/extension/avatar.php b/phpBB/phpbb/template/twig/extension/avatar.php
new file mode 100644
index 0000000000..e80357cb24
--- /dev/null
+++ b/phpBB/phpbb/template/twig/extension/avatar.php
@@ -0,0 +1,80 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\template\twig\extension;
+
+class avatar extends \Twig_Extension
+{
+	/**
+	 * Get the name of this extension
+	 *
+	 * @return string
+	 */
+	public function getName()
+	{
+		return 'avatar';
+	}
+
+	/**
+	 * Returns a list of global functions to add to the existing list.
+	 *
+	 * @return array An array of global functions
+	 */
+	public function getFunctions()
+	{
+		return array(
+			new \Twig_SimpleFunction('avatar', array($this, 'get_avatar')),
+		);
+	}
+
+	/**
+	 * Get avatar for placing into templates.
+	 *
+	 * How to use in a template:
+	 * - {{ avatar('mode', row, alt, ignore_config, lazy) }}
+	 *
+	 * The mode and row (group_row or user_row) are required.
+	 * The other fields (alt|ignore_config|lazy) are optional.
+	 *
+	 * @uses \phpbb_get_group_avatar()
+	 * @uses \phpbb_get_user_avatar()
+	 *
+	 * @return string	The avatar HTML for the specified mode
+	 */
+	public function get_avatar()
+	{
+		$args = func_get_args();
+
+		$mode = (string) $args[0];
+		$row = (array) $args[1];
+		$alt = isset($args[2]) ? (string) $args[2] : false;
+		$ignore_config = isset($args[3]) ? (bool) $args[3] : false;
+		$lazy = isset($args[4]) ? (bool) $args[4] : false;
+
+		// To prevent having to redefine alt attribute ('USER_AVATAR'|'GROUP_AVATAR'), we check if an alternative has been provided
+		switch ($mode)
+		{
+			case 'group':
+				return $alt ? phpbb_get_group_avatar($row, $alt, $ignore_config, $lazy) : phpbb_get_group_avatar($row);
+			break;
+
+			case 'user':
+				return $alt ? phpbb_get_user_avatar($row, $alt, $ignore_config, $lazy) : phpbb_get_user_avatar($row);
+			break;
+
+			default:
+				return '';
+			break;
+		}
+	}
+}
diff --git a/phpBB/phpbb/template/twig/extension/config.php b/phpBB/phpbb/template/twig/extension/config.php
new file mode 100644
index 0000000000..91b28dfccc
--- /dev/null
+++ b/phpBB/phpbb/template/twig/extension/config.php
@@ -0,0 +1,64 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\template\twig\extension;
+
+class config extends \Twig_Extension
+{
+	/** @var \phpbb\config\config */
+	protected $config;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param \phpbb\config\config	$config		Configuration object
+	 */
+	public function __construct(\phpbb\config\config $config)
+	{
+		$this->config = $config;
+	}
+
+	/**
+	 * Get the name of this extension
+	 *
+	 * @return string
+	 */
+	public function getName()
+	{
+		return 'config';
+	}
+
+	/**
+	 * Returns a list of global functions to add to the existing list.
+	 *
+	 * @return array An array of global functions
+	 */
+	public function getFunctions()
+	{
+		return array(
+			new \Twig_SimpleFunction('config', array($this, 'get_config')),
+		);
+	}
+
+	/**
+	 * Retrieves a configuration value for use in templates.
+	 *
+	 * @return string	The configuration value
+	 */
+	public function get_config()
+	{
+		$args = func_get_args();
+
+		return $this->config->offsetGet($args[0]);
+	}
+}
diff --git a/phpBB/phpbb/template/twig/extension/username.php b/phpBB/phpbb/template/twig/extension/username.php
new file mode 100644
index 0000000000..aaeaf98df2
--- /dev/null
+++ b/phpBB/phpbb/template/twig/extension/username.php
@@ -0,0 +1,85 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\template\twig\extension;
+
+class username extends \Twig_Extension
+{
+	/**
+	 * Get the name of this extension
+	 *
+	 * @return string
+	 */
+	public function getName()
+	{
+		return 'username';
+	}
+
+	/**
+	 * Returns a list of global functions to add to the existing list.
+	 *
+	 * @return array An array of global functions
+	 */
+	public function getFunctions()
+	{
+		return array(
+			new \Twig_SimpleFunction('username', array($this, 'get_username')),
+		);
+	}
+
+	/**
+	 * Get username details for placing into templates.
+	 *
+	 * How to use in a template:
+	 * - {{ username('mode', user_id, username, user_colour, guest_username, custom_profile_url) }}
+	 * - {{ username('mode', user_row, guest_username, custom_profile_url) }}
+	 * It's possible to provide the user identifier, name and colour separately,
+	 * or provide the entire user row at once as an array.
+	 *
+	 * The mode, user_id and username are required (separately or through a user row).
+	 * The other fields (user_colour|guest_username|custom_profile_url) are optional.
+	 *
+	 * @uses \get_username_string()
+	 *
+	 * @return string		A string based on what is wanted depending on $mode
+	 */
+	public function get_username()
+	{
+		$args = func_get_args();
+
+		$mode = $args[0];
+		$user = $args[1];
+
+		// If the entire user row is provided
+		if (is_array($user))
+		{
+			$user_id = isset($user['user_id']) ? $user['user_id'] : '';
+			$username = isset($user['username']) ? $user['username'] : '';
+			$user_colour = isset($user['user_colour']) ? $user['user_colour'] : '';
+			$guest_username = isset($args[2]) ? $args[2] : false;
+			$custom_profile_url = isset($args[3]) ? $args[3] : false;
+		}
+		else
+		{
+			// Options are provided separately
+			$user_id = $user;
+			$username = $args[2];
+			$user_colour = isset($args[3]) ? $args[3] : '';
+			$guest_username = isset($args[4]) ? $args[4] : false;
+			$custom_profile_url = isset($args[5]) ? $args[5] : false;
+		}
+
+
+		return get_username_string($mode, $user_id, $username, $user_colour, $guest_username, $custom_profile_url);
+	}
+}