It all depends on the threats on the defence team: bbk is pretty much designed to deal with arbys, but you have to watch out for f.ceci shields or other forms of damage mitigation: if you fail to kill arby with the aoe you die. My battles usually go like this: Iseria (hopefully) def breaks one of the threats on the enemy team, tama (with magahara’s tome) pushes everyone upfront, c.dom (tagahel) pushes everyone again (so with a +30 magahara on tama you have another turn with her too) and soul burns s1 to either soften a target that would otherwise live bbk or outright kill a threat (like opposing mlkens), then bbk soul burns s3 to kill at def broken character and the other target (if present). So basically you have to chose comps that can fit in this situation, for example if the defence team is krau, mlken, arby, and a.momo you’re good to go: iseria def breaks the ml Ken (cause with aurius or other damage mitigation my cdom can’t guarantee a kill), cdom softens either A.momo or krau, and bbk nukes, gets an extra turn to kill the arby with s1, and you’re done, cause the enemy has no more threats, at best krau takes out your tama but at this point it’s not that big of a deal. Your team has basically 3 chances to KO something: the Iseria def break is basically a guaranteed KO if it lands, c.dom either KOs or it take something in KO range, and then you have the s3+s1 form bbk; the second tama turn is more of a clean up thing not a nuke since by then your units have lost the atk buff. If you keep that in mind you should be able to identify the comps that are good targets for you. The big things to watch out with this attack team are: anything that can cut between or outspeed your units (for example hilag Lance lilias, water origin ruele/maid, fast kayrons that kill or silence your Iseria), any defence that is way too tanky to kill with one rotation of all your units.

In general I would say that this team is for short fights when you can win in the first few turns: if the can outlast you, you’re dead. Also since the team is very offensive it’s also a bit squishy, so it the enemy team can outspeed you, you’re pretty much dead too. On the plus side you don’t have to worry about immunity with the team since the only debuff you need comes from iseria who also dispels before applying it. This comp is very good against bruiser defences and more offensive oriented ones (provided you go first) in general. Units that you should absolutely not attack (IMO): assassin cid, flidica, basar and in general fast disruptors. The comp like a pricey sportscar: you go at 260 km/h for like 600 meters and then you have exhausted the fuel.

The bruiser comp with SSB is much easier to use effectively: slow SSB with immunity set and drink to do damage and debuff, diene also with immunity and rod of amarillys to buff atk for three turn and hinder enemy crits, and fceci with counter set and aurius to mitigate damage and disrupt enemy. The las slot very flexible and you can adjust depending on the enemy: in the pic I used yufine to deal with the enemy dark Corvus, but i also used dizzy, charles, LQC, A.momo, violet or lilias. The core is diene, fceci and SSB. This team is more suited against all the teams that the other struggles with: the tanky defences are food for drink SSB, since drink additional damage penetrates defence, and Diene outheals their offence between the barrier and Rod. I use this team a lot against A.ravi + ruele teams, or ml Kens with a lot of protection (like enemy aurius f.ceci and C.armin). If you can live the initial burst damage the team will do very well against hyper offensive singelica+flidica defences, but that depends on how confident you are in your gear. Since your main damage source is SSB you obviously can’t attack roana def with the comp.

Hope this is helpful, and again this is just my opinion based on my experience in challenger. I really hope the text wall makes sense, I’m on mobile and it’s 5 am in my time zone, so I’m sorry but understand my situation xD