Temporary Hit Points are a D&D 5e mechanic which provides insulation against damage in the form of hit points which can be depleted at no cost to the character. However, they are especially important to Freezo since he gained the ability Dark One's Blessing which gives him temporary hit points every time he kills a creature. This encouraged him to see most enemies, insignificant innocents, unnecessary former allies, etc, as bundles of Temporary Hit Points. (The rules actually state that creatures killed for temporary hit points must be "hostile", but God/Dave has been generous about this, and most creatures' attitude to Freezo quickly becomes at best ambivalent.)
Their first appearance in the series was when, immediately after Baston released Horsey Two-Horse into the wild, a seriously wounded Freezo killed it with an Eldritch Spear for temporary hit points.
Freezo however lost the Dark One's Blessing ability in Speaking Ten to Ten when his patron Robbie Silver declared him a Hexblade instead of a Demonic warlock. Whether or not God/Dave had Robbie do this in order to stop Freezo slaying random creatures for Temporary Hit Points will likely never be known.