Currently, the amount of offence is shown when the number of troops are entered in the war room.
My suggestion is to include an additional field which shows the remaining mod def at home with troops sent.
It is helpful for attackers to know straightaway how much def they are keeping at home when their troops are away.
Hybrids will benefit as they usually send part of the elites to attack, and there is currently no way of knowing how much defence is left without a hand calculation.
It is also helpful for the UBs to determine the feasibility of the attack while staying UB.