Gideon tribal decks in Modern have just got a new toy to play with, and it has quite a punch.
On your turn Gideon is indestructible both as a creature and as a planeswalker, which makes him really sticky. He can also give Vigilance to other creatures to protect him on opponent's turns, and if you need life, then Lifelink is another great choice.
The minus ability may be tough to reach, but it's mainly intended for control purposes, and Blackblade isn't really meant to be played in control decks. But it's not entirely impossible either.