Can never affect the colored part of the cost.

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.

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

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

The effect is cumulative.

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

A spell you cast that’s blue and red costs less, not less.

Activating the ability creates a replacement effect that acts like a shield, replacing the next time Nightscape Familiar would be destroyed that turn. This shield works against effects that try to destroy Nightscape Familiar or lethal damage that would be dealt to Nightscape Familiar.

Nightscape Familiar can regenerate even if it isn’t in combat, it’s already tapped, or it’s undamaged.

You can activate the regeneration ability even if Nightscape Familiar isn’t at risk of being destroyed.