Now, Omega's modus operandi varies depending of the form he is fighting.
As Lucifer, he can performs up to 7 attacks per round: one with Longinus, and another with six of his dragon heads. Because once a head performs a breath attack he needs some time to recharge energies to perform another breath attack with the same head (15 seconds recharge time), he only perform one breath attack per round (or one every 3 seconds). Not much beyond that, the rest depends on his powers, and note that only one head is vulnerable per round (Omega choose who is the one that is vulnerable), while the rest are invulnerable; rehardless, Lucifer is always invulnerable as long one of his heads remain active, and ignore any kind of Resistance Check unless the attacker has more Gnosis than him.
As for The Lord of Infinity, he (potentially) appears after Lucifer is defeated, and he combat still is radically different than the Lucifer's form. While relative healthy he uses his 1st level ki techs, and as he receives damage he uses the 2nd levels techs; only when his To the Limit ability triggers (25% of his maximum LP in game terms) he uses his Lv 3 techniques. Note that regradless he is a strategist and may shift between techs and other powers, and can also make use Chaos Meister (although personally this is not a good power) or using Longinus to slice through reality (this takes a full-round attack, but it ignores defender armor and works regardless of distance).