To answer this question we first take a look at the Hero Tier List that gives us a good overview over the current metagame and what heroes are hot and which are not.

Based on that, we consider a team of five heroes to focus on first. Then we present another team of five heroes for needed diversification. And finally a set of a few heroes to slot into these two teams to address some weaknesses. This gives you 15 heroes - enough to run three teams in Grand Arena and potentially Clash of Worlds (CoW).

Note that the metagame shifts constantly, esp. due to the nowadays relentless release of new heroes every two months. There is not much to do against it, but to keep your original focus for a little longer. Todays meta team will likely still be relevant tomorrow. And we will of course continously adjust our suggestions.

Finally please note that this is my opinion, based on my current experience with the metagame and the game in general. I did not test this approach as a "fresh start" in the current metagame (that is 2-3 months old), but i did "fresh starts" before with thought out strategies that turned out working very well.

There are a lot of variants of this team around: very aggressive ones with mages like Orion, Cascade and Augustus, a bit more balanced ones using Lars&Krista for example, or very slow setups relying on control heroes and healers like Polaris, Thea or Byrna. And still many more than a single picture can capture.

Which path to follow, i.e. which three heroes to accompany your Electra & Fluffy comes down to personal preference and focus, and what else you wanna do in game. Lets go through the different approaches:

1.1 BYRNA / JORGEN / POLARIS

• Arguably the toughest to beat as a defense team
• But also with the biggest issues as an attacking team with time outs - when the firepower is not enough to overcome the enemy, esp. (defense-oriented) Electra teams
• JORGEN does not need much development to be effective. POLARIS needs a little more (to stay alive), but is also still a fairly cost-efficient hero.
• It's not easy to set the heroes up in other teams - they lack flexibility.
• Three STR and two INT based heroes are more balanced than the other teams, esp. as JORGEN does not need much.
• Optional heroes are THEA, maybe AMIRA or AUGUSTUS - replacing Byrna and/or Polaris. I personally prefer Thea over Byrna, but i feel like for your first team, Byrnas offensive capabilities are needed.

1.2. ORION / AUGUSTUS / DORIAN

• Probably the easiest to overcome on defense - Isaac will hurt the team despite Fluffy being there
• Is explosive enough to not have issues with time outs when attacking
• DORIAN is a very cost-efficient hero, who only needs his 4th skill to spread his vampirism aura - even after he died
• The three heroes are very useful in many other teams - both PVP and PVE (Asgard, Adventures etc.)
• In total, four heroes are INT based, which means they fight for the same Skin Stones and Ascension mats, although DORIAN won't need much of it.
• Optional heroes include CASCADE replacing Dorian

1.3. LARS / KRISTA / CASCADE

• Is kinda middle ground regarding attack and defense. Can beat some enemy Electra-Fluffy variants, too. And overall is effective vs. a variety of enemy teams.
• The three are very synergetic, esp. thanks to the Water Mark mechanic
• But all heroes need proper development to function - which is a problem, as four heroes are INT based.

No matter how you decide, you should focus on five heroes first for a while. Once you have them on a good level and amass materials that you did not need yet - mostly AGI Skin Stones and Ascension materials - you look for the next team of five heroes. But before that, we look at what PET and FLAG you should pick for now ...

After (and maybe even while) focussing on two teams, a few adjustments might help. Both to address some weaknesses your teams might have (like Rufus!) and to offer some new use cases for your teams - for Asgard for example. The good thing is that three of the five heroes presented next do not require much development to be useful ...

These heroes are more to be considered independant than a team. What they offer:

• MORRIGAN can deal your main teams problems to kill Rufus (unless you have Cascade), who can only die to physical damage. One of her skills however prevents that, which makes her a strong counter to Rufus (to Fluffy as well btw). Fortunately, she does not need to be highly developed: give her AXEL patronage to limit incoming damage and see how she instantly heals herself up after receving a big strike, due to how good her healing scales with a low health pool.
• DORIAN (if you do not have him as part of a specific EF-team already) just needs to be developed to violet rank for his 4th skill that adds vampirism to the heroes around him - often two or three sitting in the backline. And this skill stays active after his death! It makes hard hitting backline heroes (like Orion, Augustus, Iris, potentially Jhu) very self-sustainable. He would be a very cheap replacement for Isaac in Team 2 when you do not fight mages.
• Esp. in case you have Dorian already, you could potentially go for CASCADE here too, which is also a good addition to an EF-team running Orion and Augustus. He has a similar skill as Morrigan, also countering Rufus and would therefore also make Morrigan unnecessary.
• JHU is a very solid damage dealer with multiple use cases: replacing Isaac in Team 2 when you fight non-magic teams. And he turns this team into a very strong meta team for Asgard battles vs. Osh. As a damage dealer he needs good offensive stats, but imo he does not need specific Health, Armor and Magic Defense skins and glyphs!
• MARTHA completes the Osh team. She does not need much to be useful and (just like Isaac) also does not want to be overdeveloped: keep her Health stat low, esp. never buy her Health skins and glyphs so that she can use her ultimate more regularly and give the much necessary Armor buff to her party!
• My final recommendation for Hero number 15 is GALAHAD. He is an all around powerhouse and still very relevant in the meta game. Unfortunately he needs pretty much maxed stats to shine.
• Since we are on the Osh team here, it is time to build up ALBUS who is abslutely required for high scores in Asgard. Also a great patronage pet for Sebastian, who does a lot of pure dmg.

Honorable mentions: AIDAN - a healer whos health-sharing skill allows you to run squishy heroes as tanks, offering a lot of new tactical options. KAYLA, who is a beast in attacking the enemy backline - which can be very effective vs. Electra-Fluffy teams as well as enemy physical teams that have the likes of Lara and Sebastian in the back.