The Node's ability does not target anything. You simply choose a legal creature to destroy when the trigger resolves. However, you can't choose an illegal or impossible option (per rule 60.82d, part of which is posted below), and destroying an indestructible creature is an impossible action.
608.2d If an effect of a spell or ability offers any choices other than choices already made as part of casting the spell, activating the ability, or otherwise putting the spell or ability on the stack, the player announces these while applying the effect. The player can't choose an option that's illegal or impossible, with the exception that having a library with no cards in it doesn't make drawing a card an impossible action (see rule 120.3).
So if there's a 2/2 creature and a 2/2 creature that's indestructible, you cannot choose to destroy the 2/2 that's indestructible, because that an impossible option. This is different from trying to cast a Murder on an indestructible creature, because Murder just requires a target creature, not a target creature that's destructible. Also note if there's a 2/2 that's indestructible and a 3/3 on the battlefield, nothing will be destroyed. The 2/2 indestructible can't be selected since it's indestructible, and the 3/3 cannot be selected because it does not have the lowest power among creatures on the battlefield.
This has nothing to do with indestructible becoming a keyword ability in Magic 2014.
Nathan Long
DCI Level 2 Judge
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