Attack Order Examples 

Standard Attack Moves

Most factions attack other systems simply by being adjacent to them.  Here are two examples:

In the first example the Tau player (yellow) attacks unoccupied system Golgotha (called a colonization).  He can do so because this system is adjacent to one of his systems.  The Tau player cannot attack Rhidol to the north because he lacks the ability to traverse the Great Rift hexes (those with the hazard markers).  Other valid moves include attacking Magma Codelian from Yo'vai or attacking the Catacomb of the Architects from Kor'Tal.

In the second example below the Chaos player (red) attacks the Ork player's system, Fort Nexus.  He can do so because this system is adjacent to one of his systems.   Other valid moves include (but aren't limited to) attacking Inferno Reach (from Octarius or Randoryn Alpha), attacking Seidon from Octarius, attacked Fe'saan from Octarius.

Chaos Attacks Across the Rift

Chaos factions treat rift locations as both adjacent and free movement - in this case the Red Chaos player can attack any of the green Ork systems shown but has attacked Medusa VII from Randoryn Alpha.

Eldar Attacks Through Webway Gates

Eldar factions treat Webway systems as adjacent hexes (denoted by the icon in the lower right of the hex).  In this example the Eldar player is able to colonize Commorragh because he controls another Webway gate (Crucible of Tales). 

Orks Attack Across Rift

Ork factions can also traverse the Great Rift - however they can only move through one hex of the Great Rift for free.  In this example the Ork player is able to colonize Loxar IX from T'olku.  Note that he could not colonize this system from Als'anta.