Gogo's ability targets an activated or triggered ability that is on the stack and creates one or more additional instances of that ability on the stack
While it hasnt shone after that, it was still a dominant force back in the day, and from time to time it appears in Pioneer events where the only thing stopping it from being a decent deck is its unfavorable match against arguably the best deck in the format, Izzet Phoenix
This can be used for attack or defense: either proliferate +1/+1 counters to make his allies stronger, or proliferate a poison counter to damage an enemy further
Manifesting a card puts it onto the battlefield as a 2/2 creature, and you can turn it face-up by paying its mana cost
To improve the deck, well cut the chaff and add more powerful self-mill payoffs like Cruel Somnophage and Huskburster Swarm
You can also target it with your own auras and build a Voltron version that damages your opponents without the need to attack, not to mention heroic or combo payoffs