So, what happened is that you choose not to get the creature back when the trigger resolved......
Is it a choice though? It seems like a mandatory action... I'm not saying to go back and do it though, it's my fault for missing it.
I actually wasn't done with my turn, so I assume no responses to combat, you take 3 and at the end of my turn, Meren triggers and I return the Guildmage to my hand. Does that change your turn any?
Spidey: 40
XP Ctrs: 1
Dmg from Commander: 0/21
Hand: 6
Library: 84
Commander Zone: 2BG
Battlefield:
(T,U) Swamp x2
(T,U) Forest x2
(U) Golgari Guildgate (~ ETB tapped.; T: Add B or G to my mana pool)
(U) High Market (T: Add 1 to my mana pool.; T, Sac a creature: I gain 1 life)
(T)
Meren of Clan Nel Toth Legendary Creature-Human Shaman (3/4; Whenever another creature I control dies, I get an experience counter.; At the beginning of my end step, choose target creature card in my graveyard. If that card's converted mana cost is less than or equal to the number of experience counters I have, return it to the battlefield. Otherwise, put it into my hand. )
Graveyard:
Korozda Guildmage, Altar's Reap, Lightning Greaves
Exile:
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Mooseman: 30
Dmg from Commander: 6/21
Hand: 3
Library: 85
Commander Zone:2RW
Kalemne, Disciple of Iroas (Giant Soldier, 3/3, Double strike, vigilance
Whenever you cast a creature spell with converted mana cost 5 or greater, you get an experience counter.
Kalemne, Disciple of Iroas gets +1/+1 for each experience counter you have.)
Battlefield:
(U) Plains
(TT) Mountain x2
(T) Vivid Crag (, , ~ ETB tapped with two charge counters on it. T: Add R to your mana pool. T, Remove a charge counter from ~: Add one mana of any color to your mana pool.) 2
~cntr~
(T) Drifting Meadow (, L, ETB Tapped. T: W. Cycling 2 )
(U)
Darksteel Ingot (, , Indestructible. T: Add one mana of any color to your mana pool.).
(T) Coldsteel Heart (Snow Artifact, , ~ ETB tapped. As Coldsteel Heart comes into play, choose a color. T: W)
(T) Boros Signet (, A, 1, T: Add RW to your mana pool.)
(S)
Victory's Herald (Angel, 4/4, Flying. Whenever Victory's Herald attacks, attacking creatures gain flying and lifelink until end of turn.)
Graveyard:Fiery Confluence,
Sunrise Sovereign
Exile: