Aven Mind Manipulator
Creature - Bird Wizard
Flying
Resonance — When you play a creature spell that shares a creature type with Aven Mind Manipulator, tap or untap target creature.
3/3
Agent of Fear
Creature - Zombie Wizard
Fear
Resonance — When you play a creature spell that shares a creature type with Agent of Fear, target creature gains fear until end of turn.
1/1
Abyssal Nightrider
Creature - Zombie Warrior
Fear
Abyssal Nightrider can't block.
Resonance — When you play a creature spell that shares a creature type with Abyssal Nightrider, Abyssal Nightrider gets +1/+0 until end of turn.
3/1
In the above example, there is a blue Bird Wizard, a black Zombie Wizard and a black Zombie Warrior. Note that they have the creature types that represent themselves flavor-wise. A wizard would rarely get a pump ability for example.
Then we can see that Aven Mind Manipulator and Agent of Fear could trigger each other since they're both Wizard. That's the triggering between color. And Agent of Fear and Abyssal Nightrider could trigger each other since they're both Zombie. That's for the in-color trigger. See the idea?
So now let's split the classes between each color. Let's see..