Between the echo cost and the Puncture Blast, I believe you should be tapped out right now.
Untap, upkeep, draw.
Enfeeblement (Enchanted creature gets -2/-2.) on your Slinger.
Attack with both creatures.
Done.
Turgy22: 20
Hand: 4
Library: 26
Battlefield: 8
(TTUU) Swamp x4
(U) Volrath's Stronghold (T: Add 1; 1B,T: Put target creature card from your graveyard on top of your library.)
(U) Seafloor Debris (T: Add U; T, Sac: Add Z; EtB tapped.)
(T) Phyrexian Rager (2/2; When Phyrexian Rager enters the battlefield, you draw a card and you lose 1 life.)
(T) Wurmcoil Engine (3/3; Deathtouch, lifelink; When Wurmcoil Engine dies, put a 3/3 colorless Wurm artifact creature token with deathtouch and a 3/3 colorless Wurm artifact creature token with lifelink onto the battlefield.) *#3 -1/-1 counters **
Graveyard (2): Moon Heron, Enfeeblement
Exile:
Rokapoke: 16 / 11?
Hand: 4
Library: 27
Battlefield:
(TTT) Mountain x3
(TTT) Forest x3
(U) Prodigal Pyromancer (1/1; Human Wizard; T: ~ deals 1 damage to target creature or player.)
Graveyard: Puncture Blast, Ghitu Slinger
Exile: