Planeswalker color splashing

Blorbleflorp

We all know that you can only include cards that match you planeswalker's color identity, similar to commander formats. This can be pretty frustrating, as some decks are just impossible to make. For instance, you can't make UW spirits, UB zombies, GW humans. What if we could, though, without having to spend money on future planeswalkers that may or may not be released?

I suggest that once a planeswalker reaches the maximum level, a quest would present itself to the player, where once completed would allow an additional color to be added to the planeswalker's color identity.

This may be a bit too powerful for a free feature, so another option would be a series of quests, and for each one completed, you could add one more card of a set color to your deck.

For instance, consider Jace, Unraveler. For each quest you complete, up to 5 or something, you could add 1 additional Black card to your deck, since that's his second most prominent color. For Garruk, it would be red, for Jace, Unbound, white, etc. Let me know what you think of my idea!!!

BayTamago

It could be neat if it's restricted to mono colour walkers, and only allow their secondary color.

I find that dual color PW have an insane advantage in deck building, especially since you can use cards that are multi-coloured with only one of the colours being part of the identity (IE Nahiri with BR cards)