@LichterLoh The displayed attack value is an approximation of the average damage dealt over 20 seconds (dp20).
The standard formula for splashing non-multi-target attacks is ((single target dmg+max total dmg)/2)*(20/attack speed).
Hence, based on this U3 tooltip, it should be ((48+72)/2)*(20/3)=400.
Unfortunately in this case, the displayed tooltip attack speed is not an average representation either and should as Kubik explained be rather 2,9 than 3.0 resulting in a dp20 value more closely to 415 (rounded up).
Keep in mind that the randomized 0.3-0.7 second delay was added to many entities in patch 400042, but not all of their atack values were adjusted in that patch, leading to many more cards with this misleading attack value - sometimes on top of a wrong dp20 value and incorrect tooltip. 😉