I'll just re-word it now to get that nitpicky feeling out of my brain;
"Activate only by sending 1 "The Seal of Orichalcos" you control to the Graveyard. Monsters you control gain 500 ATK. When a monster you control is destroyed, you can banish it; gain life points equal to its ATK. You can Normal Summon 1 additional time each turn. This card cannot be destroyed by card effects, also, new Field Spell cards cannot be activated."
Though if I may, this seems rather OP, much like Orichalcos Deuteros and Tritos. Even so, this is good work. Keep it up and try out some more stuff too!