A handful of the best ways are Virtue of Loyalty, Chivalric Alliance, Forth Eorlingas!, Court of Embereth, and History of Benalia
DJ Johnson: I love the black and green color combination
Although it can't prevent combat damage that would be dealt to your planeswalkers, it can still prevent noncombat damage that your opponent would want to redirect from you to one of your planeswalkers
Since only black mana can be used for Crypt Rats, it's often played in decks that primarily use black mana, as the more colors you add, the harder it can be to activate
One of the other problems that tinker has is that cube's traditionally don't have a high artifact count
It was largely designed to make mulligans less painful in Standard and Limited