These small magical vermin are paper-thin, and pale as a snowflake. Snow leeches are elemental-kin, spawned in snowdrifts, glaciers, and other places close to the elemental planes. Snow leeches feed on the body heat of living creatures, as any significant non-living heat simply kills them.
A victim is usually exposed to snow leeches when immersed in a snow drift or slush pond. The event of the snow leeches attaching themselves under the clothes is almost impossibly to spot, requiring a DC 20 WIS-perception check.
The victim of the snow leeches can easily rid themselves of them by stripping down near a heat source, as this will quickly execute them.
However, until that happens, the DC of any cold related exposure checks is increased by 5 while infested with snow leeches.
[note, this is a 5e conversion of this monster]
A ringworm is a strange creature, that appears as a plain gold ring which radiates magic. It performs identically to a Ring of Protection, and an Identify spell reveals it as such.
However, it quickly begins leech magical energy in its surroundings. During a short or long rest, a character with spell slots will lose a random spell slot, devoured by the ringworm. The ringworm will take spell slots from its wearer first, but baring that, it can leech magical energy from any creature within 60 feet. The victim of the missing spell slot simply feels it slip away.
A detect magic at this point will see the surplus energy accumulated in the ringworm, as will a followup casting of identify. However, the ringworm will have bonded with the skin, requiring either the removal of the finger, or a Dispel Magic spell. Other magical effects are absorbed by the ringworm and have no effect..