I wouldn't say a Tyrant is needed at all. A Slaughtermaster in a unit with the Standard of Discipline is much more cost effective. Not saying I wouldn't like a Tyrant, just that when it comes down to it a Slaughtermaster is usually better and it's weakness can be mitigated.
Not a bad list, although I'd drop the Tyrant. After playing a few games with a SM with crown of command inside some Ironguts with the Standard of Discipline, I've found that the Tyrant just doesn't do much. Sure he's killy, but so is everything in your army really.
Hey, there, a few thoughts on the Swarmlord. Overall, I love him, but against certain armies, he is a big worthless point sink. Unfortunately those armies are DE, and usually razorfang or leafblower lists. Against those more competitive lists, he tends to just get shot up, or totally ignored by mech DE, with the current meta, i find the flyrant much more useful for the points.
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