Show and tell

Show and Tell is one of Legacy's many archetypes. This archetype currently splits on two sub-archetypes that use Show and Tell as their core: Omnitell and Sneak and Show.

Intro
Show and Tell (SaT) is one of the main staples in Legacy. It is a card that allows all players to put a creature, enchantment, artifact, or land from hand to play. It looks a fair tactic but in reality, this card is used to "cheat" a permanent of those types into play: basically because the opponent to the player casting Show and Tell is, in most cases, going to drop a weak card and the player casting SaT is going to drop a high-cost card in play and have a huge impact on the game.

Archetypes with Show and Tell
Omnitell:

This strategy uses SaT solely to put into play the enchantment Omniscience and then start a series of different win conditions depending on each build.

Sneak and Show:

This strategy combines SaT and Sneak Attack on an Izzet (blue and red) strategy that consists on cheating a huge creature into play and start the aggro with either Griselbrand or Emrakul, the Aeons Torn.

Similarities Between Decks
Both strategies use Blue as the main color.

Both decks have access to Force of Will, which gives extra protection to the decks.

Both decks have access to Brainstorm, Ponder</c> and Preordain</c>, and that gives a fair consistency to both decks.

Both decks have access to Sol Lands (Lands that have a Sol Ring</c> effect: Ancient Tomb</c> and City of Traitors</c>), as efficient accelerators.

Omnitell
Besides the cards listed on the Similarities section, this archetype uses tutors. Usually it uses: It may also include:
 * Cunning Wish</c>
 * Omniscience</c>
 * Intuition</c>
 * Impulse</c>
 * Emrakul, the Aeons Torn</c>
 * Dream Halls</c>
 * Enter the Infinite</c>

Sample decklists can be found here:
 * Mono-Blue Omnitell
 * UR Omnitell

Sneak and Show
Besides the cards listed on the Similarities section, this archetype uses creatures and more accelerators. Usually it uses:
 * Lotus Petal</c>
 * Sneak Attack</c>
 * Griselbrand</c>
 * Emrakul, the Aeons Torn</c>

Sample decklist can be found here:
 * Sneak and Show

Analysis
The deck is fairly consistent in all decklists, but ever since the banning of <c>Dig Through Time</c> in September 2015, the frequency of Omnitell decks has dropped and the once nigh-dominance of the field by this particular sub-archetype has ended. It is still considered to be a good deck and it is often referred to as a Tier 2 deck. On the other hand, since the banning in question, Sneak and Show has become once again the preferred version of this archetype.

It is a deck that doesn't suffer from graveyard hate. It has obligatory blue included and <c>Force of Will</c> in the maindeck. This makes the combo particularly resilient, compared to other Legacy combos. This deck does suffer, on the other hand, to decks such as Reanimator. Mostly because the resolution of a Show and Tell can backfire and result in an opponent's victory (since Reanimator has big creatures in the maindeck).

Some of the best cards to sideboard against this deck are <c>Ashen Rider</c>, <c>Tidespout Tyrant</c>, or even <c>Containment Priest</c>.

In general, even though Sneak Attack doesn't keep the creature in play forever, it usually results in lethal damage with Griselbrand (for being able to draw an Emrakul with its ability) or, at least a 15-damage + Annihilator 6 from Emrakul.