Tatterkite

If Tatterkite is dealt damage by a creature with wither, that damage has no effect. It's not prevented; it just doesn't do anything. Abilities that trigger on damage being dealt will still trigger.

You can't pay a cost that includes putting a counter on Tatterkite. For example, if Tatterkite is the only creature you control, you can't cast Scarscale Ritual because you can't pay the additional cost.

A spell or ability whose effect would put a counter on Tatterkite simply doesn't affect it. The spell or ability isn't countered. If it would put counters on any other creatures, it continues to do so.