As long as this card remains face up on the field your monsters gain 500 attack point. Plus your monster are categoralized as Dark monsters. You may summon monsters in both you monster card zone and in your spell and trap cards zone meaning that you are allowed to have up to 10 monsters in play. This card my not be destroyed or have its't effect navegated by spell, trap or monster effects. if you try to activate a field spell yours gets destroyed while the seal of orichalcos stays on the field. That's what the seal does :)