I'm not doing a huge bulk of COTD entries so that tag would be wasteful. For the Fighter's Collection there's this pair of cards then one other entity that fall under my bracket.
Let's crack in to the duo, their pros and cons and what decks may or may not use them.
[AUTO]: [Soul Blast 1] When you discard this card from your hand for the cost of Calling “Ocean Transformation, Atlantis Dolphin” from the G Zone, if you have 4 or less face-up cards in your Damage Zone, you can pay the cost. If you pay it, Counter Charge 1.
Ocean Transformation, Atlantis Dolphin
[AUTO] Generation Break 1: [Choose 1 face-down G Guardian from your G Zone, flip it face-up] During a battle in which your opponent’s Vanguard attacks, when this card is placed on (GC), you can pay the cost. If you pay it for each of your Rear-guards, during that battle, this unit gains Shield+5000, and if this Unit’s Shield is 30000 or more, Counter Charge 1/Soul Charge 1.
No Robos here, heck not even Cosmic Hero. Very perplexing, what we get though a sea Voltron.
I like the art and I do like the skills as keeping on top of fuel is never a bad thing. I can't be too optimistic though as rationally you won't use these in Robos. Cosmics and Metalborgs however do present a solid case. Mostly Cosmics.
Firstly. Robos is the Meta deck and it is a deck that can ignore these cards.
Between the pair it may be counter-charge two which would easily reload Daiearth for a second firing but the heal trigger lacks that all important archetype tag which you want to keep as much as as possible and given the current build is certainly using four spots up for Luarel and occasionally additional slots for Wilking and a non Robo Stand or Draw trigger you don't want to be dropping too many Robo cards from the deck. Furthermore Daiearth twice in a match is only really used when already against a bad match up that requires you maintain some board to be able to keep up. Most of the time the single time set up is all you require and after that you open fire with Kaiser and Maxon. Robos can now operate on tight counterblast usage quite happily so keeping fuelled isn't an urgency. And honestly if you NEED more than 6 counterblast in a game piloting Robos, things aren't going your way already. (That or you are mad and running the cross ride to which I say respect and fight the good fight.)
The Metalborg deck likes to bring Heavyduke to the skirmish, however he is quite a gas guzzler. As a deck this support will be very welcome there but do be aware of that relationship between the rearguards and G-Guard's shield value. Borgs aren't known for having a decent board if they even have one at all, frequently holding off from placing units into the game until going for the play but frankly if you've gone to duke you've made that play. The problem is pacing. You'd be in late game and your board probably isn't sticking around for long if your opponent is Gear Chronicle, Kagero or anything similar or with similar elements, heck even Granblue and Aqua Force will wash away your rears.
Which brings us over to Cosmic Heroes who are the one in most dire need of anything to get them over right now. Same issue with Rear survivability as Metalborgs but there is resist options to bring into tow if need be. Ignoring the problems faced by whatever the opponent is for a moment though. Cosmics will take anything they can get and that includes this new support being beneficial to them.
What I will say about this card duo, go ahead and use them- for anything other than Dimensional Robos.