This card is cumbersome to use on its own, since it has a high Soul cost, requires you to maintain 5 unflipped damage, and is generally easy to predict and play around by your opponent since it also needs to hit. However, this card supports several Royal Paladin cards very well, such as Young Pegasus Knight, Great Sage, Barron (who both benefit from the once-per-turn Soul Charge), Gigantech Dozer (who gains power when there are 6 or more Royal Paladin in the Soul, Knight of Godly Speed, Galahad (whose effect requires at least 6 Royal Paladin in the Soul, and Lohengrin gives you a chance of charging the previous members of the chain in case you've missed them), and of course Soul Saver Dragon.
Pairing this Unit up with Young Pegasus Knight or Borgal will probably allow you to consistently reach 21000 attacking Power. Alternatively, using Little Sage, Marron will at least allow it to hit for 20000.
You don't have to attack the Vanguard to activate his skill; an attack to the rearguard will work too.
If you fill the soul too much you can ride more than one Soul Saver Dragon, to have constant attacking units with great power.