Final code for myCRED Tutorial - http://mycred.me/tutorial/how-to-make-your-custom-hook/

mycred-hook-template-tutorial

// Register Hook
add_filter( 'mycred_setup_hooks', 'register_my_custom_hook' );
function register_my_custom_hook( $installed )
{
	$installed['complete_profile'] = array(
		'title'       => __( '%plural% for Profile Completion', 'textdomain' ),
		'description' => __( 'This hook award / deducts points from users who fill out their first and last name.', 'textdomain' ),
		'callback'    => array( 'my_custom_hook_class' )
	);
	return $installed;
}

// myCRED Custom Hook Class
class my_custom_hook_class extends myCRED_Hook {

	/**
	 * Construct
	 */
	function __construct( $hook_prefs, $type = 'mycred_default' ) {
		parent::__construct( array(
			'id'       => 'complete_profile',
			'defaults' => array(
				'creds'   => 1,
				'log'     => '%plural% for completing your profile'
			)
		), $hook_prefs, $type );
	}

	/**
	 * Hook into WordPress
	 */
	public function run() {
		// Since we are running a single instance, we do not need to check
		// if points are set to zero (disable). myCRED will check if this
		// hook has been enabled before calling this method so no need to check
		// that either.
		add_action( 'personal_options_update',  array( $this, 'profile_update' ) );
		add_action( 'edit_user_profile_update', array( $this, 'profile_update' ) );
	}

	/**
	 * Check if the user qualifies for points
	 */
	public function profile_update( $user_id ) {
		// Check if user is excluded (required)
		if ( $this->core->exclude_user( $user_id ) ) return;

		// Check to see if user has filled in their first and last name
		if ( empty( $_POST['first_name'] ) || empty( $_POST['last_name'] ) ) return;

		// Make sure this is a unique event
		if ( $this->has_entry( 'completing_profile', '', $user_id ) ) return;

		// Execute
		$this->core->add_creds(
			'completing_profile',
			$user_id,
			$this->prefs['creds'],
			$this->prefs['log'],
			'',
			'',
			$this->mycred_type
		);
	}

	/**
	 * Add Settings
	 */
	 public function preferences() {
		// Our settings are available under $this->prefs
		$prefs = $this->prefs; ?>

<!-- First we set the amount -->
<label class="subheader"><?php echo $this->core->plural(); ?></label>
<ol>
	<li>
		<div class="h2"><input type="text" name="<?php echo $this->field_name( 'creds' ); ?>" id="<?php echo $this->field_id( 'creds' ); ?>" value="<?php echo esc_attr( $prefs['creds'] ); ?>" size="8" /></div>
	</li>
</ol>
<!-- Then the log template -->
<label class="subheader"><?php _e( 'Log template', 'mycred' ); ?></label>
<ol>
	<li>
		<div class="h2"><input type="text" name="<?php echo $this->field_name( 'log' ); ?>" id="<?php echo $this->field_id( 'log' ); ?>" value="<?php echo esc_attr( $prefs['log'] ); ?>" class="long" /></div>
	</li>
</ol>
<?php
	}

	/**
	 * Sanitize Preferences
	 */
	public function sanitise_preferences( $data ) {
		$new_data = $data;

		// Apply defaults if any field is left empty
		$new_data['creds'] = ( !empty( $data['creds'] ) ) ? $data['creds'] : $this->defaults['creds'];
		$new_data['log'] = ( !empty( $data['log'] ) ) ? sanitize_text_field( $data['log'] ) : $this->defaults['log'];

		return $new_data;
	}
}

When presenting points in settings, we should never use format_numer(). Log template fields should always be escaped when inserted into a field.