Since Karlach gives all attacking creatures first strike as well, this makes your creatures even better attackers since they'll have a lower chance of dying in combat
Targeting a creature with an ability was trivial, and with Springheart Nantuko backing Nadu up, you had a constant source of new creatures to target with abilities that cost zero mana to essentially draw your entire library
(They create a Clue token.) II, IV Create a 2/2 black Alien Angel artifact creature token with first strike, vigilance, and "Whenever an opponent casts a creature spell, this token isn't a creature until end of turn." I, III Choose target creature
Still, I think there are going to be enough situations where neither mode is useful and this is a miserable card when that happens
Mouse Armor Mouse Armor is a 2 Cost Steel item card
Instead, swap them out for additional copies of Peter Pan Lost Boy Leader and Kit Cloudkicker