Unhallowed mayhem

[Fenster]

2{Heartless summoning} + {Triskelion} + {Mikaeus the unhallowed}

Or {Mikaeus the undead} + {Pentavus}

[BoyMac]

Triskelion + mikaeus work infinitely alone.

[JaCe BeLeReN]

Triskelion + mikaeus work infinitely alone.

{Heartless Summoning} is to kill them when they have no +1/+1 counters.

[Fenster]

With the summoning triskelion gets -2/-2 wich is his base toughness + mikaeus's +1/+1 so when he comes back from undying he has only the counters keeping him alive meaning when the counters are gone he dies then comes back again with another 4 counters.

[BlackJester]

Triskelion + mikaeus work infinitely alone.

{Heartless Summoning} is to kill them when they have no +1/+1 counters.

You use the last +1/+1 to kill itself.  {Heartless Summoning} does make them both cheaper to cast, though, so it's more icing than function.