Spells that target this creature cost less to cast.
The cost reduction applies to spells cast by any player.
The cost reduction will be no matter how many times the spell targets the same Spellwild Ouphe.
The spell may have any number of other targets; that won’t affect the cost reduction unless the spell targets other Spellwild Ouphes as well. In that case, the spell costs less to cast for each different Spellwild Ouphe it targets.
less to cast.