Senrethen, the formless

This creature can survive 3 tuns as a 0/0 before it
dies.
Whenever there is an artifact or an artifact creature
on the battlefield that you opponent controls, they
must pay double its mana cost or they sacrifice it
and Senrethen, the formless gets +1/+1
counters equal to its
toughness if it is an artifact creature, or its
converted mana cost if its a artifact.
{4} Turn target creature into an artifact creature.