By the time this card runs out of nodes, you should have all the colors you need
Castle Garenbrig can help ramp out big creatures extremely early on and is an easy pick for green decks
However, if you do, and all of those targets are illegal as the ability tries to resolve, it won't resolve and none of its effects will happen
Like Eerie Tempo, Eerie Control can benefit from splashing in red for access to more damage-based removal and the Room-based effects
But my experience in the last few years has been that you should probably be packing a few such win conditions somewhere in your list, even if you dont plan to aggressively tutor them up every game
However, over the years I think there are a few exceptionally cool creature types that have fallen through the cracks, and I really hope we see more of them in the future