Calliope
- Impossible to counter using Axis armour
- Rework barrage to Katyusha levels
- HP/Armour to Priest levels
All these are a good option, but with all those changes, you should lower the cost and CP. At the moment it is a very late piece that in the factions SOV/WEHR they have their pieces to leave much earlier and at lower cost with which they are very spamables.
In shot: nerf barrage, chassis and reduce costs and lower CP
Aura effects
- Soviet forward HQ
I do not know how to nerf his aura, but the change will be from OP to UP so the commander will be a trash and the players will not get the maximum performance from that OP ability. IMO so I suggest that that ability would be changed to call-in T-34/85, which would make a commander totally useful.