Moodglo sucks and everyone knows that.
This card is part of the the Terrible Series and was made by This Works.
When Moodglo is on the field the owner may pay 100 Points to halve the hearts of any card on the field. This does not count as an attack and Moodglo can still choose to attack when this effect is used.
This effect can be very useful against cards with a high heart value or to damage cards that have an effect when attacked, a good example would be the Whomp.