Dragon Light Rk 6 2400/2100
So here we have the last of the trinity of horribly designed Dragons and I don't think he is all that bad honestly. First for 2 level 6 dragons you can summon any dragon from the deck. Now this may sound pretty bad as it's a lone fire for dragons without the tribute, but it's restrictions is what really balances it for me. For using that eff he himself can not attack that turn and the monster he summons has 0 stats and thus essentially only useful for it's eff and as an Xyz Material for later summons.
Now that essentially leaves this guy with 3 targets that are really worth it. Of course the first is the obvious REDMD allowing you to get another Xyz going most likely and allowed for the OTK if you had 2 of these guys by making Gustav and removing the 0 stat restriction by giving you knwo a dragin that has stats along with this guy. The next target is just members of his own archetype as they will usually be able to be used right away and ignore the fact it's a monster on the field. Thirdly, GEPD as it just bypasses the 0 stats eff and he is decent against Xyzs. That's really it besides a few stragglers you could summon but probably wouldn't because this still really has to be used in his own archetype.
Now the real troublesome part about this guy is the card that removes the last restriction of him not being able to attack with the Gaia overlay. Now I don't really call this a fault of atum but more Gaia so form your own opinion about that.
Now that I got the obligatory stuff about this card out, I have to say that I honestly really dislike him. Without the Gustav OTK available to them anymore, this guys purpose is to just make another rank 6 Xyz along with him. Now that's fine and dandy with Gaia but I really don't like him all that much so I often feel I'm just summoning this guy out of an obligation versus the actual benefit. Though with the new Blue eyes support and the E-tele engine BESD is easy enough to get out with this guy and with Birdman tagging along you can do some garbage plays with him to get a full stated REDMD, 2 reborns and probably a synchro as well.
So who knows how the future of Hieratic decks will look in the future, but I feel Atums only roll will really just be to get REDMD to the field fast like always and get banished/Gaia'd.