Why not do this: Carriers. My ecksbawks hueg creatures, can have biological turrets on top. Already tough as hell, and provides a safe breeding ground for creatures in the field.
Anti Air weapons: Flack seed spitter. Bio-laser(corneas focus light, after all). Flying suicide creatures, or flying creatures that latch on and start drilling/biting.
Anti Armor weapons: Solid shell spitter. 'Shaped charge' seeds. High intensity thermal ray(HITR). Acid. Big claws, pincers, talons, etc.d
Anti Infantry: Flamethrowers! And rapid fire thorn spitters. Poison. Fire bombs. Serrated things. Acid.
I can think of a LOT of creatures that could fulfill countless roles. Whether they be flying bomb-dropping jelly-blimps, or parasitic insects that lay eggs in our targets, the eggs eat them from inside out, and can jump onto other enemies. But it's better to make them as they're going to be needed(right before, not when).
One thing to remember is that we can't stop every type of attack. Death magic is our bane. Just as water and order are, and vice versa. Does that mean we should avoid making use of a domain because we could fight that enemy? No. They aren't going to abandon their domains, neither should we. Rather, we should find ways to avoid their domain. Kill death priests with fire. Use strangler vines to kill paladins of order. Turn water into puddles, or boiling water, or a hundred other different things.