Can the Gaunt Summoner of Tzeentch on Disc be taken in a Disciples of Tzeentch army?

[frostyeel]

The Legion of Chaos coalition ability reads

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2 in every 4 units in the army can be a coalition unit from the Slaves to Darkness faction that has the Mark of Chaos keyword. Those units must be given the Tzeentch Mark of Chaos keyword.

The Gaunt Summoner on Disc does not have the Mark of Chaos keyword so obviously can't be taken as a coalition unit. Clear and done.

But I'm confused as to whether it can be taken as an ally. The Disciples of Tzeentch allies include 

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Slaves to Darkness (excluding units that can or must be given a Mark of Chaos)

My common sense initial interpretation was that the Gaunt Summoner of Tzeentch on Disc has the Tzeentch keyword, and so has a mark of chaos, and thus can't be taken as an ally. So no way to take it at all in a Disciples army. But reading things more literally, I'm not seeing anything in any rules that says having the Tzeentch keyword is the same as having a Mark of Chaos (much less being able or required to be given one). Units that can or or must be given a Mark of Chaos have both the Mark of Chaos keyword and the Mark of Chaos ability on their warscroll, and the Gaunt Summoner on Disc has neither. So I'm seeing one interpretation that would allow taking it as an ally.

Going along with that, if it is able to be taken as an ally, I don't see anything in the core rules that prohibits allies from benefitting from allegiance abilities. It seems the intention was that the new ally and coalition rules would not allow any units to be able to be taken as an ally that shared a keyword with the faction, but the Gaunt Summoner on Disc seems like it was a bit forgotten.

[Arzja]

Pretty sure the Gaunt Summoner of Tzeentch can just be taken as a part of a Tzeentch army. No allying or coalition needed.

[NinthMusketeer]

5 hours ago, Arzja said:

Pretty sure the Gaunt Summoner of Tzeentch can just be taken as a part of a Tzeentch army. No allying or coalition needed.

That is how it used to be. With 3rd they changed allegiances so they work off what is in the battletome instead of by keyword (not happy about it myself, but I can see why they did it). The summoner on disc can no longer be taken in Tzeentch lists proper.

It CAN be taken as an ally, which means it could not be given enhancements (artifacts, spells, etc). This is because it is a StD unit, a valid ally, and the "Mark of Chaos" exception is defined by a certain ability which he does not have.

The "can or must" bit is referring to some units, like cultists in an Idolators army, have the choice to take a mark while most units with the rule are required to pick one of the options. 

Edited July 29, 2021 by NinthMusketeer