You can Ritual Summon this card with "Earth Chant". If this card is Ritual Summoned using a "Soldier of Stone" monster as a Material, declare 1 card type (Monster, Spell, or Trap); all cards you control are unaffected by your opponent's card effects of the same type while this card is on the field. Once per turn, during the Battle Phase (Quick Effect): You can change the battle positions of all face-up monsters on the field. If this card is sent to the GY: You can add 1 Rock monster from your Deck to your hand.
The competitive value of this card comes from the following:
I. The protection effect can stop certain decks (Sky Striker, rokket, etc.) from touching your field. Also, you can easily use a 'Sentry Soldier of Stone' as the material, and then just revive it.
II. The protection effect can be combined with other cards like 'Imperial Order' or 'Royal Decree'. The protection effect can also stack if you have multiple copies of this card on the field (that were all Ritual Summoned with a 'Soldier of Stone' monster).
III. The battle position effect can not only protect your monsters from a single powerful (non-Link) monster's attack, but also proc 'Attack the Moon!' during your opponent's turn.
IV. The search effect doesn't care how this card is sent to the GY. Destroyed by battle, Ritual material to summon another copy, Link material for 'Missus Radiant', discarded as a cost, milled by 'Foolish Burial', etc. It's not locked at once per turn like so many other search effects, either.
V. Even if you don't intend to Ritual Summon this, it can still be useful. For example, play this card in a 'Lightsworn' Deck, mill or discard this card ('Lumina, Lightsworn Summoner' can help with the latter), search 'Gigantes', banish this card (or 'Gem-Knight Seraphinite') from your GY to summon it, and then ram 'Gigantes' in an opponent's stronger monster to basically 'Heavy Storm' the field.