This could be it.
Untap, upkeep, Draw
Island
Opal Lake Gatekeepers, evolving the Crocanura
Done
Spidey: 6
Hand: 5
Library: 47
Battlefield:
(T,T) Forest x2
(T,T) Island x2
(U) Centaur Courser (3/3)
(U) Crocanura (2/4 from ctr; Reach; Evolve) *1 +1/+1 ctr*
(S) Opal Lake Gatekeepers (2/4; When ~ ETB, if I control two or more Gates, I may draw a card)
Graveyard: Archweaver
Exile:
================================================================
Mooseman: 20
Hand: 1
Library: 47
Battlefield:
(UUTTT) Plains x5
(T) Island
(U) Azorius Cluestone (, A, {T}: Add {W} or {U} to your mana pool.{W}{U}, {T}, Sacrifice ~: Draw a card. )
(T) Silvercoat Lion (Cat, 2/2, )
(T) Silvercoat Lion (Cat, 2/2, )
(T) Sunspire Gatekeepers (Human Soldier, 2/4, When Sunspire Gatekeepers enters the battlefield, if you control two or more Gates, put a 2/2 white Knight creature token with vigilance onto the battlefield. )
(S) Azorius Justiciar (Human Wizard, 2/2, When ~ enters the battlefield, detain up to two target creatures your opponents control. (Until your next turn, those creatures can't attack or block and their activated abilities can't be activated.))
Graveyard:
Exile: