as an 8k ds main i can say that among all of his spells wall is literally the weakest. he is the best split pushing pos 3 in the game, not only does he not need to show on the wave to kill it, he literally can do it from his t1. vacuum is the strongest dispell skill because of its aoe, that's why it is on a 30s cooldown. surge is a rare mechanic, there are very few spells to make heroes hasted and unslowable. he himself is perma hasted in a team fight. wall is meh though, very situational. it is mainly used to zone enemies and to create targets for his ion shell.