None of Elderwood Scion’s abilities affect abilities that target it.

Aura spells require a target when they are cast. Elderwood Scion’s cost-reduction ability will affect Aura spells cast targeting it.

Spells you cast that target Elderwood Scion will cost {2} less to cast even if those spells have additional targets. The same is true for spells your opponents cast costing {2} more.

Elderwood Scion’s cost-reduction ability can’t reduce the colored mana requirement of a spell.

Elderwood Scion’s cost-reduction ability can apply to any cost of a spell, including additional or alternative costs.