Nothing official has been announced as the second half of DT07 isn't even out yet for us, but I think it's a fairly safe assumption that we will continue to get OCG DT cards via Hidden Arsenal sets. I must say I'm looking very forward to this upcoming Hidden Arsenal and think it will impact the meta quite a bit. I think the last Hidden Arsenal that really had an impact on the game was HA04 which had Trishula in it. 5 and 6 had a few notable cards, but nothing too major in the grand scheme of things. I believe 7 could have as much impact as the very first HA set, if not more. I'll list what cards I'm looking forward to and I'm sure others as well (order is not indicative of anything, at least to me).
1. Tinplate Goldfish
Lv4/Water/Machine
When this card is Normal Summoned: You can Special Summon 1 Level 4 monster from your hand.
The last time I played any sort of Gadget variant seriously was when I was down in Texas. I played the shit out of Machina Gadget but eventually moved on to better decks. For the past few days I've been testing out "Goldfish-Machina-Gadgets" using ideas from OCG builds I have seen, and I must say I really do enjoy playing the deck. Essentially this is Double Summon with a body that lets you go into almost any Rank 4. Not having to wait a turn to set up a Gigant play is pretty sick, and at the very least the 2000 DEF isn't bad at all.
2. Daigusto Emeral
Rank 4 (2 Lv4) /Wind/Rock
Once per turn: You can detach 1 Xyz Material from this card to activate 1 of these effects.
● Target 3 monsters in your Graveyard; shuffle all targets into the Deck, then draw 1 card.
● Target 1 non-Effect Monster in your Graveyard; Special Summon that target.
There's no denying that this guy has been anticipated for quite a while by at least those who knew of it's existence in the first place. This is a mini-Pot of Avarice and an enabler to many potential combos. I know there are a few FTK/OTK-ish strategies out there that use this guy as the key recycling component - oh boy lol.
3. Lavalval Chain
Rank 4 (2 Lv4)/Fire/Sea Serpent
Once per turn: You can detach 1 Xyz Material from this card to activate 1 of these effects;
● Send 1 card from your Deck to the Graveyard.
● Choose 1 monster from your Deck and place it on top of your Deck.
A big part of me feels that if we had this card last format, Inzektors would've won a YCS. This card is basically a Foolish Burial with a body, and in Inzektors has the added application of stacking DAD on top of your deck. Or Dragonfly, or whatever you needed lol. Even outside of Inzektor, any deck being able to tutor a specific monster to the top of their deck has a lot of potential applications (Infernity Archfiend anyone?). Like Emeral, I think he falls into the same category of "degenerate combo enabler".
4. Molten Conduction Field
Send 2 "Laval" monsters from your Deck to the Graveyard.
I know Laval players have just been itching for this card to come out. This allows you to easily dump Lakeside Lady and Handmaiden and what ever else to set up your Rekindling plays. Whether Laval becomes a top tier deck in the TCG, it's hard to say. I don't think I've seen it top anything in OCG since last format. However, one must accept that another sacky deck can be added to our list of ones we already have. *Derp* Shooting Quasar for game? :/
5. Evilswarm Heliotrope
Dark/Rock/1950 Normal beater.
I know you may be thinking "OK, a 1950 beater, so what - Alexandrite Dragon and Gene-Warped Warwolf are bigger", but the Rank 4 Evilswarm XYZ's must also be considered when taking this card into consideration. After all, "Verz Laggia" was a thing in OCG last format. Of course it has the benefit of outright running over TKings.
6. Evilswarm Ouroboros
Rank 4 (3 Lv4)/Dark/Dragon
Once per turn: You can detach 1 Xyz Material from this card; activate 1
of these effects. Each of these effects can only be used once while this
card is face-up on the field.
● Target 1 card your opponent controls;
return it to the hand.
● Send 1 random card from your opponent's hand to
the Graveyard.
● Banish 1 card in your opponent's Graveyard.
Trish is back, kinda. This guy is key in the Six Sam Hand loop (check Youtube) and who knows how else this could be abused.
7. Evilswarm Ophion
Rank 4 (2 Lv4 lswarm)/Dark/Dragon
Neither player can Special Summon Level 5 or higher monsters while this card has Xyz Material. Once per turn: You can detach 1 Xyz Material from this card; add 1 "Infestation" Spell or Trap Card from your Deck to your hand.
This can potentially shut decks down but may not be as good as it could be in this heavy XYZ era of the game. However, not letting your opponent summon Hyperion, BLS, DAD, Megalo, relevant Synchros, etc, isn't too shabby.
8. Evilswarm Bahamut
Rank 4 (2 Lv4 lswarm)/Dark/Dragon
Once per turn: You can detach 1 Xyz Material from this card to target 1 face-up monster your opponent controls; discard 1 "lswarm" monster, and if you do, take control of that opponent's monster.
This is a true "Snatch Steal"-like monster, and unlike Tragoedia you don't have to match levels or anything like that. I guess it's pretty similar to Big Eye but you can bring it out via a single Rescue Rabbit play lol.
9. Evilswarm Thunderbird
Lv 4/Dark/Thunder
During either player's turn, when the effect of a Spell, Trap, or Effect Monster is activated (except during the Damage Step): You can banish this card you control. During the next Standby Phase, return this card that was banished by this effect to the field, and it gains 300 ATK. You can only use the effect of "Evilswarm Thunderbird" once per turn.
I remember seeing this card splashed into many OCG decks last format as a 3-of, and you can quickly see how annoying it can be with a beater that can keep on coming back, Standby after Standby. I'm not sure if there are any rulings out there that make this card suck now, as I don't recall seeing it in lists all that much right now. I guess Wind-Up and Water are just too good/played in OCG right now.
10. Constellar Ptolemys Messier 7
Rank 6 (2 Lv6)/Light/Machine
You can also Xyz Summon this card by using 1 face-up "Constellar" Xyz Monster you control as the Xyz Material, except "Constellar Ptolemys Messier 7". (Xyz Materials attached to that monster also become Xyz Materials of this card.) You cannot activate this card's effect the turn you Special Summon this card this way. Once per turn: You can detach 1 Xyz Material from this card to target 1 monster on the field or in either player's Graveyard; return it to the hand.
Constellar is a decktype I remember playing against randomly on DN one time a while back. I'm still not sure on what all they "do", or hope to do. This guy specifically, most likely has application in something like Chaos Dragon in that they can actually go into Rank 6. If it survives a turn you can grab back a milled/destroyed BLS or bounce a problem monster or what have you.
I know there are even more cards that are at least somewhat relevant in this set, and that is saying a lot. When was the last time a Hidden Arsenal set had 10+ relevant cards in it? lol. Realistically I probably won't be getting a box of this, more like order 3x Goldfish, 2 or 3x Emeral, 2x Chain, and maybe a set of Thunderbird as singles and call it good. However I'd say buying a box of this sounds a lot more feasible than buying a box of HA2, 3, 5, or 6 when they were new.