Convergence of Dominion
A Convergence of Dominion is what you call a group of Starsteles in a battlefield formation. There are no consistent or orthodox placement of these constructs. They can be placed anywhere, so long as each model must be set up wholly within 12" of one another. The exact reason why is unknown, but it may be likely due to the need to maximize the construct's role as a support unit.
As such, it can be stated that inactive Starsteles are Convergence of Dominions in dormancy. Requiring the aid of a Cryptek to fully utilize their full potential on the battlefield. So far, a maximum of three Starsteles is needed to make a Convergence of Dominion per battle. As such, only one formation of a Convergence of Dominion is applicable.
Crunchwise, the Starstele and the Convergence of Dominion are one and the same as the structure cannot function to its fullest extent by itself. The constructs are first and foremost, a unit support buffer that gives surrounding Necrons significant leadership bonus. As such, it is recommended to spread these structures out to maximize their cover distance and sphere of influence. The rules even state it out flat, in which each model within the construct's influence is treated as a separate unit. They will give 2 leadership to any unit within 6" and in most cases, it should increase your Necrons to leadership of 12. As aforementioned, these structures can move, albeit with help from a Cryptek. But their movement range is infinite, so are you going to honestly complain?
Their Transdimensional Abductor is a nasty weapon. The weapon is an Assault D3 weapon with S4, AP-3, D3 stats. They should be able to easily clean up any horde infantries. However, the only downside is their pitiful range of 12". Combined with their general immobility (Outside of the translocation protocols of course) and the need to distance themselves from each other, these structures can be surprisingly quite vulnerable if left unattended.