Once you have infinite G mana, use Sisay to search for Nylea, Keen-eyed. From there you mill non-creatures and put all creatures into your hand. This gets you Kamahl, and Walking Ballista.
While this is one combo, there are other viable GW combos that more revolve around Sisay being able to tutor them and shifts away from the low cost combo.
Other Combos i'm considering: Karn, Silver Golem /Karn, the Great Creator + Gideon, Martial Paragon + The Chain Veil + Total Mana Dorks/Rocks that can produce 4+ mana
With this combo as long as you can generate 4 mana, you can get infinite mana. The combo goes; Karn animates the Chain Veil and any rocks, tap your dorks/rocks for mana, activate Chain Veil, use Gideon's +2 which will untap all of your creatures which includes the Chain Veil, and repeat this as needed meanwhile you can tutor for cards with Sisay. Even if you have only 4 mana, Gideon's ability increases the p/t of all your dorks everytime the +2 is used. Therefore, once you activate the ability enough times, you can actually -10 Gideon to tap down any blockers that your opponents may and then you can beat your oppenents over the face with a llanawar elf, or a mana vault.
Selvala, Explorer Returned + Umbral Mantle + Angel's Grace + Infinite Mana
This wincon requires you to already have infinite mana as Selvala isn't the most reliable to combo with Umbral Mantle. The combo is to use Selvala's Parley ability, which is a mana ability and doesn't use stack, to have everyone reveal and draw the top card of their deck. Always holding priority, use Umbral Mantle to untap Sylvala. Once you draw the Angel's Grace, you cast it so you can't lose the game and continue holding priority and continue with the parley and the untap. What is interesting about this combo is the fact that your opponent's cannot interact with the combo once it starts except for the cast of the Angel's Grace and even then only triggers and morphs can interact with it.
1 Captain Sisay
Artifact
1 Chrome Mox
1 Lotus Petal
1 Mana Crypt
1 Mox Amber
1 Mox Opal
1 Grafdigger's Cage
1 Mana Vault
1 Sol Ring
1 Lightning Greaves
1 Talisman of Unity
1 Trinisphere
Creature
1 Walking Ballista
1 Avacyn's Pilgrim
1 Birds of Paradise
1 Elvish Mystic
1 Fyndhorn Elves
1 Llanowar Elves
1 Mother of Runes
1 Quirion Ranger
1 Collector Ouphe
1 Containment Priest
1 Devoted Druid
1 Ethersworn Canonist
1 Gaddock Teeg
1 Grand Abolisher
1 Hushbringer
1 Kataki, War's Wage
1 Phyrexian Revoker
1 Priest of Titania
1 Saffi Eriksdotter
1 Spirit of the Labyrinth
1 Thalia, Guardian of Thraben
1 Vizier of Remedies
1 Aven Mindcensor
1 Dosan the Falling Leaf
1 Eidolon of Rhetoric
1 Eternal Witness
1 Hushwing Gryff
1 Reclamation Sage
1 Recruiter of the Guard
1 Selvala, Explorer Returned
1 Yisan, the Wanderer Bard
1 Linvala, Keeper of Silence
1 Nylea, Keen-Eyed
1 Kamahl, Fist of Krosa
1 Elesh Norn, Grand Cenobite
1 Carpet of Flowers
1 Survival of the Fittest
1 Sylvan Library
1 Living Plane
Instant
1 Crop Rotation
1 Enlightened Tutor
1 Nature's Claim
1 Noxious Revival
1 Path to Exile
1 Swords to Plowshares
1 Veil of Summer
1 Worldly Tutor
1 Eladamri's Call
1 Once Upon a Time
1 Force of Vigor
Planeswalker
1 Karn, the Great Creator
Sorcery
1 Green Sun's Zenith
1 Finale of Devastation
1 Regrowth
1 Eldritch Evolution
1 Idyllic Tutor
1 Armageddon
Land
1 Arid Mesa
1 Bountiful Promenade
1 Canopy Vista
1 Cavern of Souls
1 Command Tower
1 Dryad Arbor
1 Eiganjo Castle
1 Flagstones of Trokair
5 Forest
1 Gaea's Cradle
1 High Market
1 Horizon Canopy
1 Marsh Flats
1 Misty Rainforest
1 Okina, Temple to the Grandfathers
3 Plains
1 Razorverge Thicket
1 Savannah
1 Strip Mine
1 Sunpetal Grove
1 Temple Garden
1 Verdant Catacombs
1 Windswept Heath
1 Wooded Foothills
So the main way the deck combo's off is with Vizier of Remedies + Devoted Druid infinite mana combo with Kamahl, Fist of Krosa or Walking Ballista as your mana sinks. The way that this deck assembles the vizier combo is through the multitude of tutors that [sym=gw] has to offer, with the main one being Yisan, the Wandering Bard who is tutorable with Sisay.
The ideal Yisan line is as follows:
Verse 1 – Quirion Ranger to return a forest and untap Yisan for Verse 2 (if quirion ranger is in hand or in play get Mother of Runes)
Verse 2 – Devoted Druid or Vizier of Remedies if the druid is in play
Verse 3 – Recruiter of the Guard to fetch for Vizier of remedies.
Once you have infinite G mana, use Sisay to search for Nylea, Keen-eyed. From there you mill non-creatures and put all creatures into your hand. This gets you Kamahl, and Walking Ballista.
While this is one combo, there are other viable GW combos that more revolve around Sisay being able to tutor them and shifts away from the low cost combo.
Other Combos i'm considering:
Karn, Silver Golem /Karn, the Great Creator + Gideon, Martial Paragon + The Chain Veil + Total Mana Dorks/Rocks that can produce 4+ mana
With this combo as long as you can generate 4 mana, you can get infinite mana. The combo goes; Karn animates the Chain Veil and any rocks, tap your dorks/rocks for mana, activate Chain Veil, use Gideon's +2 which will untap all of your creatures which includes the Chain Veil, and repeat this as needed meanwhile you can tutor for cards with Sisay. Even if you have only 4 mana, Gideon's ability increases the p/t of all your dorks everytime the +2 is used. Therefore, once you activate the ability enough times, you can actually -10 Gideon to tap down any blockers that your opponents may and then you can beat your oppenents over the face with a llanawar elf, or a mana vault.
Karn, Silver Golem/Karn, the Great Creator + Nissa, Genesis Mage + The Chain Veil + Gaea's Cradle + 5 or more creatures
The above combo, similar to the Gideon combo uses the planes walker to untaps things that generate mana as well as the Chain Veil. Unlike Gideon, this combo will only spin its wheels if you do not net mana.
Selvala, Explorer Returned + Umbral Mantle + Angel's Grace + Infinite Mana
This wincon requires you to already have infinite mana as Selvala isn't the most reliable to combo with Umbral Mantle. The combo is to use Selvala's Parley ability, which is a mana ability and doesn't use stack, to have everyone reveal and draw the top card of their deck. Always holding priority, use Umbral Mantle to untap Sylvala. Once you draw the Angel's Grace, you cast it so you can't lose the game and continue holding priority and continue with the parley and the untap. What is interesting about this combo is the fact that your opponent's cannot interact with the combo once it starts except for the cast of the Angel's Grace and even then only triggers and morphs can interact with it.