So, I’m F2P, do I qualify to comment?
You have to be somewhat realistic as we’re talking about event portals. For someone who is just starting, and NOT spending money, they’re not going to summon from them period. There’s no way you can complete enough of the challenges with 2* heroes with a smattering of 3* heroes without item support which you won’t have the resources to use as you spend your time building your buildings. By the time you actually get enough coins to actually summon from these portals, you’ld likely already have a decent set of 3 and 4 star heroes. Think about S2 and S3, do you think you could collect 100 coins easily (going through 34 stages) without a decent set of heroes? You also have to consider WE limitations as well, as you don’t have a lot to start. Same with challenge events: they run once a month. Assuming you have a beginning roster of 2 and 3 stars, maybe you can finish the rare for 3 coins. Maybe not, I’m not going to run to find out. Epic challenge? Not likely. I remember going through at least 3 or 4 challenges before being able to complete the epic challenge at which point I’d have some 4 star heroes and unlikely to care about building up more 3 star heroes.
Basically, by the time you actually get the coins to summon, you’d probably already have a decent set of heroes from your TC, assuming you build up your building correctly.