These are a few of the tactics that I have figured out during my long stay on Cradle. Feel free to share your own.
Wave rider:
Trojans are powerful enemies and one should generally avoid getting hit. However, Trojans also come with support in most situations and staying mobile while in a huge encroaching crowd can be difficult. This particular tactic uses the Trojan's power to your advantage. The Trojan swing and Buff both have large knockback, you can use this in conjunction with a strong shield to ride that attack out of bad situations. Enemies have trouble tracking you and the speed at which you travel makes shield damage from traps minimal. A similar tactic can be employed with standard lumbers but for the ones with stun and another status it is recommended to only use a shield that offers the correct resists.
Center of Chaos:
Wolvers tend to be moderately troublesome enemies, the biggest problem is how fast they move. The Center of Chaos tactic relies on this while other standard strategies are hindered by it. Blast bombs have a strong knockback and damage throughout the blast. Wolvers will dash and teleport into the bomb area. For the best results get a team of gunners to stand in the blast radius to draw Wolvers in.
Shot lock:
Devilites are tough enemies for any class. They're ranged so sword and bomb users have trouble getting up close and they dodge gunfire. There is one gun family that they have trouble with though and that is the Callahan. This gun can pin them down for a short bit but thanks to the 2-shot clip it won't be long. In order to take full advantage bring a Blitz or Plague needle and switch shoot with the Callahan. You will bypass the clip limits of both guns and with the pinning power of the Callahan you can make full advantage of the Autogun's power.
Compound clearer:
This is a super simple strategy and requires skill in bombing. This strategy uses a Voltaic Tempest and a Vortex bomb of any kind, though the Obsidian Crusher is recommended. Place the Voltaic tempest to shock the monsters and make them more manageable, then follow up by dropping a Vortex inside the Haze. The Shock from each enemy spasm will harm nearby enemies and if you are using an Obsidian Crusher the poison will increase the amount of Shock damage dealt.
I heartily endorse the Wave Rider tactic. For example, it's useful in the last fight of depth 27 of Firestorm Citadel. If you're surrounded by monsters, and you don't want to run across the spikes or fire? Just let the trojan send you to the other side of the room.
Now I'll mention the tactic that I always mention...
Infantry/Artillery: This one is good for Heart of Ice and other difficult fiend levels. One knight (infantry) stands in front, repeatedly shield-cancelling the first stroke of Final Flourish/BTB. His job is defense --- interrupting monsters and occasionally absorbing hits. Another knight (artillery) stands in back, releasing Blitz Needle charges. She is offense, killing everything with impunity because she is protected by the infantry.
And this one is a non-obvious part of brandish-spamming...
Tunneler: Suppose you're using knockback-heavy attacks such as a brandish charge, Divine Avenger charge, or long-distance pulsar shots. Run into the knockback area, where there are no longer any monsters. This tactic helps you cut through crowds to free space, for example.