In general, I would look at these two factors when looking to include cards not of your tribe's creature type: Is this creature so strong that it, on its own, is generally stronger than my tribal creatures when they are receiving bonuses and/or empowering my other cards
In the mana article, we adjusted our probability of success by increasing the number of successes in the population
Cascade The main difference between discover and cascade is that the former is a keyword action as part of the resolution of an ability
Each Collector Booster contains 15 Magic: The Gathering cards and 1 Traditional Foil double-sided token, with a combination of 5 cards of rarity Rare or higher and 25 Uncommon, 47 Common, and 1 Land cards
Each deck contains 15 new-to- Magic Commander cards from Innistrad: Crimson Vow , plus a foil-etched display commander
Gamechangers for Isshin Yuriko, the Tiger's Shadow If you like ninjas, then Magic: The Gathering has a brilliant commander option