The spirits of fallen battlemages can serve their guilds as familiars by joining with any physical form.

Sunscape Familiar

Defender (This creature can't attack.)
Green spells and blue spells you cast cost {1} less to cast.

The List

Planeshift

(Walls can't attack.)
Green spells and blue spells you play cost o1 less to play.

Can never affect the colored part of the cost.

If a spell is both green and blue, you pay {1} less, not {2} less.

If this card is sacrificed to pay part of a spell’s cost, the cost reduction still applies.

The generic X cost is still considered generic even if there is a requirement that a specific color be used for it. For example, “only black mana can be spent this way”. This distinction is important for effects which reduce the generic portion of a spell’s cost.

The lower cost is not optional like with some other cost reducers.

This can lower the cost to zero, but not below zero.