Many things in the world can block magic power, for instance, mochi juice is a very outstanding anti-magic material. Large castles are almost all constructed using mochi juice as a binder, such castles can very well withstand the impact of magic and Dou Qi, remaining strong.
However, mochi juice merely resists magic, it cannot completely stop the infiltration of magic power.
There are hardly any items that can prevent the seeping of magic power, not even gemstones or crystals, those products of dragons. Gemstones can maintain their magic power for an extended period, but the reason lies more in the fact that gemstones have a concentrating effect, allowing them to automatically absorb the free magic power in the air.
Crystals have this effect too, though it is very weak, and once the Dragon Magic Power is exhausted, they lose this property.