@TigerDevil, I TC20 odds of a 5* appear to be 5%, and generally accepted as better odds than an epic, event, or elemental summons.
So that bumps your .143% to .238% if they are added to the TC20 pool. If all 12 current ones were added to the pool, getting one would have 1.43% odds.
Still, I’d note that TC20 doesn’t give you a shot at the current HotM, event heroes, or the wabbits which guess I’d call seasonal heroes in case there are ever any more like those three.
TC20 means if you play for a long enough, you have a good shot at getting “normal” 5*s without spending much (or even any) money, making it possible for f2p players to build a really good competitive team…but leaving lots of good stuff that free players are very unlikely to get, as epic hero summon tokens are not handed out often, and have quite low odds as you point out.
I actually think this is a decent balance that makes the game worthwhile for both f2p and p2w, including differing levels of paying, which all work for some players. And I think this (ultimately) is a good thing. Without paying players, the devs don’t eat, and we don’t have a game at all … but I’m not interested in getting into a competition of how much I can pay–I can’t stomach winning that one!