Great Wall is horrible, but it doesn't hurt you. It could be possible to use it with something, but I'd say Great Wall is only slightly worse than Snowfall, since both basically do nothing, but Snowfall MIGHT end up helping pay to keep a Reality Twist or something out. Sorrow's Path takes up a land drop and does nothing, unless you activate it, in which case it hurts you and is far too situational to use. Train was able to build a deck based on making that damage a good thing, rather than a bad thing. I'll bet he could make something to work with Great Wall too. The Trooper is terrible, but it doesn't give you a personal Armageddon when it comes into play. For four mana, Aven Trooper is a 1/1 flyer with an ability you will probably never use. For four mana, Wood Elemental is a 0/0 that does nothing except die, unless you are willing to give up an untapped Forest for each point of power and toughness it gets, which is such a bad deal that it almost makes the Trooper look good.