The Chaos Gods only devote a small fraction of their attention to the material universe from time to time. They're too busy playing the eternal Great Game against each other in the infinite Warp. I don't think they would ever care to personally get involved in a minuscule conflict such as this. The most you are going to see of their power on the battlefield would be "gifts" to their followers (mutations, boost to attributes, daemonic weapons/armor, etc) and maybe send a few Daemons in to stir things up, but that's pretty much it.
Only "gods" you may see on the battlefied are : - avatar of Khaine for Eldar - great demons : avatar of chaos gods for Chaos Marines (there are 4 indeed : one for each god) Apart of avatars there are greatly powerful units which can appear on the battlefield in needed time like : - a squiggoth for Orks - the sanguinor of Space Marines Blood Angels - a prince demon for Chaos Marines - the swarmlord of Tyranids - an autarch of Eldar
Isha is still alive and kicking. Well, as much as one can be kicking while being force-feed Grandfather Nurgle's latest plagues.
Nah, a Stompa for Orks ! Dat's a real Idol of Gork (or Mork). Squiggoth's just a fraggin' huge meatball wiv' teeth (and angry).
Well that's just the way Nurgle shows his affection. The tub of moldy lard has a stinky crush on Isha.
All this talk of gods when the only one needing mention is blessed Nurgle. I have composed an ode to our magnificent lord of Plagues (clears throat) Nurlglish lord within the warp How do I love thy poxes with gentle care you bless our skins and turn unbelievers into corpses The greenskin gods this mork and gork they are philistine raging beasts with no true art and no great scheme will their stupidity never cease? The eldar, sick and thin and weak hiding in twisting webways their gods are dead, yet still they seek they look upon their last days The other three are mere pretenders to our Nurgle's throne they fight and squawk, bawl and yell over realms they cannot own And on far Terra, old and rotting the corpse god there remains but Nurgle's hordes will descend upon him and leave him but a stain So tremble ye unfaithful scum and look upon our lord Nurgl'eth his name, lord of the seven be faithful and adore
Pretty much this. Though I'm sure it's been stated somewhere that they simply can't enter the material universe in the first place. Partly due to well, each being a part of the immaterium, and secondly because they are much too powerful to remain outside of it. Generally the less powerful a deamon is, the longer it can maintain a shape outside of the warp - Apart from a few key figures and Daemon Princes ( Who are anchored in both realms ). So it's logical that the same restrictions would apply for the gods themselves.
