The only fun things I can think of for the Baneblade transports is the stacking buffs for those inside it. What you can do in the Stormlord is:
1) Take 3 Command Squads with 4 plasma guns, and 3 Heavy Weapon Squads with 3 heavy bolters. Then you make them all Cadian so you can use the new strats.
You can move the Stormlord 10 inch and then use the new Shock Troops stratagem. This makes it count as stationary, as well as the units embarked, meaning all 7 units can now RR1 to Hit. They also all get +1
AP to their weapons, as modifiers to the transports affect the units inside.
That's not all though. If you trigger Overlapping Fields of Fire, then get the Stormlord to shoot that target for the +1. Then all units inside also get the +1 modifier, however, they're not restricted to shoot that target as they're not under the effect of the stratagem. So, those 6 units inside can shoot anything else with a +1 to Hit.
2) You make it a bomb truck. You can stick 3 Cyclops demolition vehicles in there and because their detonation is a shooting attack they can blow up using the firing decks, as well as use the Stormlord to measure the radius.
They can also benefit from Shock Troops, RR1 to Hit from stationary, and +1 to Hit.
* * * * *
Will these win you games? Probably not, but they're probably the best you can do with a Baneblade at the moment.
If you also don't believe me, I'll link you the rules.
https://wahapedia.ru/wh40k9ed/the-rules/advanced-rules/#Shooting-Whilst-Embarked-on-a-Transport
Specifically these three points.
If the TRANSPORT model made a Normal Move, Advanced, Fell Back or Remained Stationary this turn, embarked units are considered to have done the same when they make ranged attacks.
Any abilities (including Detachment abilities) that models in an embarked unit have, or that their weapons have, continue to apply when they make ranged attacks.
If a TRANSPORT model is under the effects of a modifier to its ranged attacks (such as a modifier to its hit rolls, wound rolls, etc.) the same modifier applies each time an embarked model makes a ranged attack.