I have to second that point. Came here just to post and complain about that. Its a severe breach of the game rule mechanics. Its completely non sensical. If you compare the phrasing from quint and SoW the inconsistency is even more obvious.
Quint
"Grant immortality to the target creature. The target creature can not be targeted."
SoW
"The target creature gains +4/+0 and now deals spell damage if immortal."
How can you target a card that can not be targeted?
Forgive me for being a TCG nerd for a moment here. But in any
real card game, the rulebook always has a section saying "If the text on a card conflicts with the rules, the card always takes precedence. For example, in MTG, if a card says ignore the mana cost, you ignore the mana cost. In Yu-Gi-Oh, there is a card called Counter Counter, and it is a normal trap card, that can be played in response to a counter trap card. In Cardfight Vanguard, the Angel Feathers focus on defying the thought that anything in the damage zone is untouchable. My point is this seems to be along the same lines. Think of it as this...
Immortal effect:
"Card cannot be targeted."
SoW:
"This card may target an Immortal creature. Give target creature +4|+0, and if it is Immortal, it now does spell damage."
They probably just couldn't fit the words "This card may target..." on the card, or couldn't figure out how. Of course there always is the chance they just forgot to say that. But the bottom line is this effect is implied and any player who reads this should be able to tell what the implied rule is. By not having that implied rule, this card just gives +4|+0, now for 3 that is not terrible, but it's no shard. Very few card games have cards that do nothing, but without implied rules like this there would be plenty more. Cards that say this card can attack twice, but the rules say creatures can only attack once, so it only gets one attack. No, just whenever you see a card that defies the rules, mentally input one sentence at the end. "This card defies rule in question."