ESPRcon

scroll rack seems good with land tax and the fetchlands

legacy merfolks, tempo thresh/rug tempo, team america, new horizon (though that deck isnt as popular as it used to be)

I would add goblin guide. I think you can play less than 24 lands, considering you have nothing above 2 mana.

it surprises me that its Ub fish and it doesn't run perish in the sb.

you need more lands.
I would splash either black or white for creature removal and planeswalkers. I would also cut the random creatures. Control decks play to types of creatures: stallers (ex wall of omens) and win conditions (ex baneslayer angel)

nice!

I think that 19 lands isnt enough, because you are running both pox and smallpox and you have no way of bringing lands back from the graveyard

I would add more lands, you are trying to cast 7 and 10 drops after all

I would get some sort of dual lands, otherwise nice deck

I would play 4 goblin guides. The card is insane. I would also add hellspark elemental. I would also cut the deck to 60 cards by taking out browbeat and Quest for Pure Flame.

but, in my opinion, a control deck doesn't want a aggressive start. It wants to grind the opponent out and delver seems quite bad at that.
Just my 0.02

it seems strange to me to play delver in a control deck. I would play 4 dissipates before playing 4 negates.
I would also cut the sorins vegeance's and divinations and play think twice and forbidden alchemy instead.
I like all your other card choices

the creatures are fine, but I would cut the fogs and get more spells like Lead the Stampede and explore/harrow/cultivate since it seems to be what a green deck wants to be doing

As far as I understand, tempo is all about making the opponent react to your threats and generally hinder and destroy his gameplan. RUG tempo is a good example:
(on the play)T1: delver of secrets
T2: delver is a 3/2, attack. Then ponder. stifle the opponents threat, then on his turn daze his spell
T3: burn a creature down, swing with delver, play goyf.
If I understand tempo correctly its all about advancing your own board position, while destroying your opponents. To do this you have to play aggro-control.

It looks like a good deck, my only suggestion whould be to add some shcoklands and fetches

I agree that the deck is far too slow, but I dont think control is completelly unplayable. You need swords to plowshares though.
Some of the cretures are to slow or ineffective for legacy

First of all: cool deck! I would cut the dreads. For two reasons: first of all you only run 20 lands and second of all the vigors and necroplasms seems to be enough.
just my two cents

I was thinking something like misty rainforest. If you are not going to play with fetchlands then I would recommend swapping brainstorm for preordain.
Just my two eurocents

you need more lands. Also if you play brainstorm, fetchlands are a good idea

the plan is to kill people before the lategame. Its a tempo deck. If a merfolk deck gets to the late game it will use the mana to pump coralhelm and activate mutavault.