In the Void, using color in a Sister's Realm damages it. This is why Donor is the "forbidden" glyph - giving literally destroys the world. For every five drops of color, the Realm loses a micron of health - in other words, for every drop of color invested in any glyph, the Realm loses 0.02% health. Damaging a Realm has a number of drawbacks and only one minor positive effect; hence, it is in the player's best interest to preserve the world by using color sparingly.

There are two ways to minimize this damage. One is to make full use of the benefits of silver and gold, which decrease the amount of damage to the world and decrease the amount of color needed to open a Sister's hearts respectively. Another is to only use a Sister's poisonous colors in her realm. This reference guide focuses on the second way.

The primary intent is not to walk you through the process - the game is quite helpful in explaining basic controls - but rather to provide an easy reference for which color to use where, as it is troublesome to remember the set of poisonous colors for each sister. Without further ado:

Using the favourite colors of a Sister in her realm causes 20% more damage to it. Using the colors poisonous to her is 20% less damaging. In the interest of preserving the world, it is then advantageous to only plant trees of a color poisonous to the Sister who owns the garden, and to only draw glyphs using poisonous colors to the Sister in whose Realm you're currently fighting.

Name | Colors to feed her (BAD FOR REALM) | Colors to grow and use in realm|
Ava -------- Amber and Violet ------------------------- Azure and Gold
Aya -------- Amber and Crimson --------------------- Silver and Gold
Echo -------- Silver and Violet ------------------------ Crimson and Azure
Eli -------- Crimson and Silver ------------------------ Gold and Violet
Ima -------- Azure and Emerald ---------------------- Amber and Violet
Ire -------- Amber and Gold --------------------------- Emerald and Silver
Una -------- Azure and Crimson --------------------- Gold and Violet
Uta -------- Emerald and Silver -----------------------Amber and Crimson
Yani -------- Azure and Violet ------------------------ Amber and Emerald
Ole -------- Gold and Violet --------------------------- Azure and Crimson
Death/Nameless -- Emerald and Gold ------------ There are no colors poisonous to her, so grow whatever you want - just try to avoid Emerald and Gold (remember, favored colors do 20% more damage to the Realm!)

Lookup by color:
Amber - grow in the realm of Irma, Uta, Yani
Azure - grow in the realm of Ava, Ole
Crimson - grow in the realm of Uta, Ole
Emerald - grow in the realm of Yani, Ire
Gold - grow in the realm of Ava, Aya, Eli, Una
Silver - grow in the realm of Aya, Ire
Violet - grow in the realm of Eli, Irma, Una

Donating color to a Sister causes 50% more damage to the Realm. Attacking enemies causes 25% more, and growing trees - 25% less.

The effect of damaging a Realm is threefold:
-The only beneficial effect is that the brother guarding it will weaken. On the downside, damaging a Realm below 30% will force the brother connected to it to attack you.
-Damaged Realms generate less color.
-Damaged Realms spawn more and stronger predators.