OK
Let's call that 'tyrant' a 'bruiser':
H: Bruiser - great weapon = 138
And you have to take a unit of bulls:
C: 3 Bulls - bellower, ahw = 127
Which leaves 375 points to buy another core (ironguts probably) and other smashy things, including possibly more kit on The Man.
Here's where I'd go, most likely:
H: Bruiser - fistful, great weapon, heavy armor, sword gnoblar = 162
C: 4 Bulls - bellower, ahw = 166
C: 3 Ironguts - bellower = 154
C: 8 Trappers = 48
S: 2 Leadbelchers - bellower = 120
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650
Bruiser > Rocking a giant stick to smash things and the fistful for a rerolled break test if/when things go south. Can run with bulls or guts. Sword gnob was to burn 5 points, but potentially entertaining!
Bulls > They fight, a lot. 16 attaks + bull charge should hopefully dent something.
Guts > Standard
MSU guts, mostly here for escorting the bruiser into the front of tough things, flanking by themselves or getting lucky and nabbing cavalry.
Trappers > Awesome unit of awesome tiny things. 101 uses, all mostly annoying to your opponent.
Belchers > Small versatile unit, should hurt particularly @ 650 where unit strength is low, so pop-guns can reap. Maybe. I often never shoot mine any more, using them instead as light cav.
But that's just my take, using the units I trust after a long time of being dissatisfied with my fatties' performance
- Salvage