If your problem is an approaching enemy force that you want to stop in their tracks then the Gooey Blob might be the solution. A Growth capable of self-replication, both living and Undead can be ensnared by the green gunk with the former suffering attack damage for as long as they are held prisoner, even until death.
A Chaos Spell, three of these multi-tile affecting sticky abominations can be grown to disable even large numbers of foes with its Mega-spell, Gooey Mess. However, blobs are vulnerable to attack spells and their ability to harm the living nullified if paralysed. Therefore, despite being an easy measure to deploy with a Casting Chance of 70% or Mana Cost of 30, precisely when to use them may not be as straight forward as it first appears for those looking to maximise their tactical advantage.