That means the first ability on Deathrite Shaman doesn't count (since it targets something), and the +1 on Xenagos, the Reveler doesn't count, since loyalty abilities can't be mana abilities
Grave Danger (Blue-Black) Have siblings Gisa and Geralf raise you an endless army of zombies
But since my creature has tantrum, I can assign 3 damage to your 3/3 and the remaining 2 damage to you (the attacking player), and I get to punish you for attacking with your tiny creature into my tantrum creature
The impact is minimum, as many times it can be an easily overseen detail, or it can have the best of the outcomes, by making something more visually understandable without messing up basic concepts
You can also play a grindier game with cards like Opposition and Niv-Mizzet, Parun to give the deck staying power if the aggressive route doesnt work