A technique which he creates to greatly restrain himself. This technique is called the Cromwell. In itself, it seals away a vast majority of Dhargasin's powers, allowing him to sneak into places undetected, give himself a challenge, and disables access to more powerful abilities which he can access.
Currently, even when restricting 90% of his power(which the level 10 seal), Dhargasin is still able to use all of his abilities, just not to a devastating level.
This Cromwell Release requires 3 seconds to activate, and requires his clones' cover to back him up. He, however, does not use this to allow access to his reserves, preferring to use his other seals instead.
This technique is only available from the depths of the Sage's sealed library, and unknown to most, energy can actually be stored within this seal.