As a table-wide meat-shield, it could be viable, actually. 72-wide gives 5 ranks and change. You could lob Skaven indirect fire overtop of it, and be able to fend off any charge for a couple of turns. In the mean time, you're casting Wind of Undeath to create units in front of your wall to flank anything holding off a frontal assault, and as soon as the edges start to collapse, you can scamper around the flanks with frenzied rats.
Of course, you could get silly, and use Lore of Light and Danse - WS10 with Pha's means most troops are hitting on re-rolled 5's, while you're hitting back with 5 attacks hitting on 3's with ASF and re-rolls per front model.
Hero support would be:
two Forbidden Lore (Light) vamps on horses
one Necro (Danse)
one BSB (Flag)
Stick in a bunker of your choice, and add another counter-offense unit.