You do not need to actually use the consumable in-match, just equip it when you start a match or tower. Get a consumable, any consumable, equip it to a slot on your tower runs and you should get this in no time.
Easy Fatailities in Versus also count as consumables, but only if you use them.
If you want to farm this, load the consumable up when you follow the 250 towers achievement guide and you should have it easily before you finish 250 endless reloads.