Ancient Apparition is a very fun support hero to play with, mostly because it requires good individual skill and precision to time his high range strong spells that cost a lot of mana. He can create quite a chaos in the laning stage and in team fights. Chilling Touch and Ice Vortex are both very good damage amplifiers, so partnering him with another good ganker is very efficient in dominating the lane. Cold Feet is very useful with another hero that provides lock down, thanks to the bonus 4 seconds freeze.
He is not good at all in one on one situations, because of his low hit points, slow movement speed, lack of burst spells and no escape mechanism.
The most interesting part of the hero is definitely his ultimate, Ice Blast. It is a global AOE spell that deals damage over time, prevents healing and regeneration and kills enemies low on hitpoints. If landed, it stops opposing team from pushing and is very useful in team fights especially against lineups with healing capacity. Sniping enemy heroes that are trying to escape anywhere on the map is definitely the most fun part of this spell.
Named Kaldr, he is an image projected from outside time, he springs from the cold, infinite void that both pre-dates the universe and awaits its end