To finish intermediate, you’ll want at least an entire team of 4* at 3/60. It might be difficult without being able to omit the reflect color, though. Next reflect is purple, so it’s not ideal using Rigard, but still better than an offensive purple. Too, you should know, this next event won’t be featuring a compass as the completion reward; Pirates is the only event out [currently] that offers a glove instead of a compass.
As for leveling:
Green: I’d actually get Caedmon leveled to 60 before bothering with Evelyn. Evelyn can’t be used in intermediate, and your 4* Caedmon will have better stats than Evelyn when he’s at max vs her 3/70. Plus, Evelyn works best paired with another green, so Caedmon can fill that role for you.
Red: Boldtusk is an amazing hero, and one I’d prefer to level before Kelile always, but you might struggle in the event running two healers. Even still, Boldtusk is a vital 4*, one of the best, and you’ll use his attack buff (and heal) nearly everywhere. Amazing for Titans and events. Kelile is good for a fast sniper hit, but she’s no where near as awesome as BT. It depends on your priorities, but if you want a more versatile hero for Titans, I’d go BT. If you really just want more offensive heroes, then I spose you could do Kelile (still, my vote is for BT).
Blue: Honestly, since you don’t have many hitters on your team, I’d do Sonya first for the fast hit and dispel. Usually I’d prefer Kiril first, but that would be way too many healers right away. Although, Kiril is just as useful as Boldtusk in versatility (for Titans and events), and you’ll need several healers for war, but for now- I’d stick to Sonya, then do Kiril after.
Yellow: Honestly, I would drop Hu Tao. He’s too slow, and doesn’t hit hard enough, to deserve using unfarmable mats on him to max. Wu Kong is much, much better. He doesn’t hit, but no hero in the game buffs attack as much as Wu does; he’ll be amazing for events, Titans, and completing levels/raids above your pay-grade. Wu for sure.
Purple: Your only options are Rigard, so him lol. He’s actually a really amazing healer/cleanser, so you’ll use him quite a bit. During the Pirate event though, if you do bring him in, just make sure to keep an eye on him. All purple tiles that hit purple enemies will reflect back onto him, meaning he’ll take damage from all of those hits. It’s still doable with a reflect healer, just more difficult. Something to keep in mind.
Once you get those heroes leveled, your defense team could be:
Rigard-Sonya-Boldtusk-Hu Tao-Caedmon
Not ideal, but could work. For defense, you want your tankiest hero in defense/health as your middle hero (the tank), that either hits fast/hard/ails or that supports their flanks so they can do the same. Next to the tank, you want wreak havoc heroes that you definitely want to have charged, so ones that control mana, lower defense, buff, or heal work best. In the wings (far corners), usually you’ll want fast to very fast heroes (preferrably snipers), since they don’t take much to charge, and can snipe out the remaining enemies. The Al moves from left to right, so you’ll want cleanses, dispels, attack buffs, and defense downs on the left.
For Titans, you’ll want to stack as many of the strong color vs the Titan as you can, and filling in the rest with neutrals. Once you have more options, you’ll want to bring in the heroes with the highest attack stats; Titans are all about tile damage. Every Titan fight should also have Wu Kong on your team, and either Kiril or Boldtusk to heal and buff attack. The remaining three spots go to your strongest heroes that are strong or neutral vs that element. Once you get a defense down hero, you’ll want them in on every Titan fight as well. Elemental defense down heroes work well for the element they’re strong against, and Evelyn is currently your only one, so always make sure to bring her in vs blue Titans. An ideal Titan team would look like:
Heal(/& Preferrably Attack Buff) (Boldtusk/Kiril) - Elemental Defense Down (Falcon/Jackal/Evelyn/Arthur/Panther) - Defense Down (Wilbur/Isarnia/Athena/Grimm/Gormek/Tiburtus) - Highest Attack Stat that’s strong vs Titan - Tile Damage Buff (Wu Kong/Tarlak)
Event teams, for now, you’ll just use whatever heroes are your strongest. Eventually, you’ll remove the reflect color, and instead, stack against it. For example, this upcoming event is reflect purple, so you’d remove your purple hero and add in another yellow. You could do more than one yellow too, but I’d suggest only adding one if you’re new to stacking.
You could practice stacking (once your heroes get developed) in raids by stacking vs the tank. To do that, you would remove the color that’s weak against the tank, and bring in two heroes that are strong vs the tank. If you seem to like that strategy, and it works for you, you could take it up a notch and add in another stack, either by tripling the strong color, or stacking another color on top (usually vs a flank).
There’s a lot of other information I know I’m leaving out, but those were all the first to come to mind. If you have anymore questions, or are curious about anything else, always feel free to ask. Also, there are several awesome posts here on the forum too- basically anything there is to know E&P related.
Good luck in the event 
