Activate Wall of Roots by putting two -0/-1 counters on it (due to Loading Zone), adding .
Activate Tayam by paying 3 and removing three counters from creatures you control.
In response to Tayam's ability, activate Ashnod's Altar by sacrificing Wall of Roots, adding .
Resolve Tayam's ability, milling yourself three cards and returning Wall of Roots from your graveyard to the battlefield with two vigilance counters on it due to Tayam and Loading Zone.
Repeat.
This loop creates an engine of constant recycling by feeding a sacrificed creature right back into play. Wall of Roots generates the initial green mana by placing -0/-1 counters on itself, which Loading Zone doubles to fuel Tayam, Luminous Enigma's activation cost of removing three counters. While Tayam's ability is on the stack, Ashnod's Altar sacrifices Wall of Roots for colorless mana to help pay for the ability, sending the wall to the graveyard. When Tayam resolves, it mills cards and returns Wall of Roots to the battlefield, where Tayam's static ability and Loading Zone work together to ensure it enters with extra vigilance counters, ready to be sacrificed and recurred all over again.