Zetta primarily uses melee attacks. He initially attempts to close with B.J. to deal damage with his gargantuan claws. To defeat Zetta is easier than it may seem, once you are aware of the correct approach. Note that you must enter the Veil to see Zetta in his true form in order to damage him. Don't waste your ammo when you are in the real world.(you should see what will happen during the cutscenes) First, fire at Zetta until the pieces of his armored carapace are knocked off. Surprisingly enough, both him and the ceiling conduits (described below) absorb more damage from the physical bullets of the MP 40 and the MP 43 compared to the (normally) more powerful energy weapons like the Particle Cannon. Thus, it is better not to expend the ammunition of your powerful weapons here. You can also use Empower to blast his carapace apart more quickly. Zetta moves at average speed but might occasionally catch you due to his huge reach, so use Mire in short bursts to escape him if he comes too close.Once his carapace is blown off, he will go to one of the three Veil energy conduits, which re-forms his carapace and heals him. This is the moment to strike and do some real damage, but not by firing at him: when he jumps onto the platform, fire at the conduit on the ceiling above Zetta. The target area can be seen highlighted in red when B.J is in the Veil. The conduit will explode violently and damage Zetta. Enraged, and his carapace re-formed, he will attempt to attack B.J. again. After the destruction of each conduit, Zetta will fire off Veil energy attacks in some form, that cause serious damage but can be evaded. First is a solid ring of expanding energy at chest level, which you can duck under. The second is a solid ring of energy that runs along the ground this time; jump over this one. The third are scatterings of energy projectiles fired in a diagonally tilted ring; you can predict their path and jump to the side to evade it. Using Mire is not necessary but can make these attacks easier to recognize dodge. Once familiar with the enemy's various attack patterns it is possible to score a perfect victory over this boss. Repeat this sequence, destroying each conduit in turn while fighting Zetta in between, and you will destroy the beast. Note that the same active Veil conduits that heal Zetta will also recharge your Veil bar extremely quickly, faster than a normal Veil pool. After a conduit is destroyed, the platform will still recharge your Veil but only at the same speed as a normal Veil pool. The best time to replenish your medallion is when Zetta crawls to a platform to heal; you can quickly move to a different platform while firing at Zetta's conduit from there. See: Wolfenstein (2009)