No matter when they’re printed, the various Charm cycles that have been printed over the years have appealed to pretty much all types of players. They serve many functions, and the Charm cycle in Return to Ravnica block is no different.
Let’s focus on Boros Charm today. It has some pretty nifty abilities. That second one is fairly intriguing, making all of your permanents indestructible for that turn. It’s a pretty good way to counter a wrath effect (or coupled with an Obliterate), but being indestuctible doesn’t mean it’s invincible.
For instance, being indestructible doesn’t really help out your planeswalkers. See, an indestructible permanent still receives damage like normal. So if you block your opponent’s 5/5 with your indestructible 2/2, your 2/2 will still take the five damage, it just won’t be destroyed by it. Likewise, if you deal damage to a planeswalker, it will still cause that many loyalty counters to be removed from it, even if it’s indestructible. And the state-based action that puts a planeswalker into the graveyard for having zero loyalty counters on it isn’t destruction, it’s just put into the graveyard.
So if your opponent just cast a Magmaquake and you’re hoping to save your planeswalkers with your Boros Charm, that won’t really work. They’ll still take damage like normal and, if they’re reduced to 0 loyalty, they’ll go to the graveyard.