You have at least six artifact and/or creature cards in your graveyard.
Mana Needed
({3} magic symbol) ({B} magic symbol) ({B} magic symbol) ({G} magic symbol) plus enough mana to pay for commander tax if applicable available.
Steps
Cast
Aatchik either from your hand or from the command zone by paying ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) ({G} magic symbol) plus commander tax, if applicable.
When
Aatchik enters the battlefield, its first ability and
Cloudstone Curio trigger.
Resolve the Cloustone Curio trigger, choosing to return nothing to your hand.
Resolve the
Aatchik trigger, creating a 1/1 Insect creature token for each artifact and/or creature card in your graveyard.
When the Insects enter the battlefield,
Cloudstone Curio triggers that many times.
Holding priority, activate
Phyrexian Altar six times by sacrificing six Insects, adding ({3} magic symbol) ({B} magic symbol) ({B} magic symbol) ({G} magic symbol) .
When the Insects die,
Aatchik's second ability triggers six times, putting six +1/+1 counters on
Aatchik and causing each opponent to lose 6 life.
Resolve the
Cloudstone Curio triggers, returning
Aatchik from the battlefield to your hand with the first trigger and returning nothing to your hand with each subsequent trigger.
Repeat.
Notes
If you have seven or more artifact and/or creature cards in your graveyard, this combo will net infinite tokens, mana and +1/+1 counters on