Giving your creature indestructible can be a lifesaver if you need other stax pieces (I am assuming if you play Boromir, Warden of the Tower , you are playing a stax deck) to stay alive, or if you just want to beat down someone and survive a board wipe
Essentially, if your opponent gives one of your characters the Reckless keyword, you have until the end of your turn to figure out a way of exerting that character if you want to stop them from challenging
Grim Bauble What most people read as a sorcery speed Disfigure is actually my sleeper pick for best Cube card of the year
Landfall is an ability word that designates an effect that's triggered by putting a land into play
Credit: Wizards of the Coast Done for the Day FromTheShire: Lots of flexibility here to get exactly what you need in a given situation
I have won a lot of games simply keeping an Elvish Reclaimer untapped and inactive to serve as a response to whatever my opponents would be doing