This deck is an idea I got from someone on Reddit, although the exact list is my own creation. The idea is simple: start with the regular Black-White Tokens deck, and add the card Polymorph to search up an Emrakul, the Aeons Torn.
The BW Tokens part of the deck is pretty straightforward; you bring tokens into play with Spectral Procession, Lingering Souls and Raise the Alarm, and boost them with Intangible Virtue and Sorin, Solemn Visitor. There are many decks that simply cannot handle tokens, in particular midrange/control decks without wraths (such as Jund, Abzan and Grixis), and aggro decks without evasion (including Infect, Affinity, and Hate Bears).
However, the regular Tokens deck is weak to combo decks, because apart from a few discard spells it doesn’t have ways to interact with those. This is where Polymorph comes in; you can now use your discard to slow the combo opponent down a bit, and then put Emrakul, the Aeons Torn into play to race them.
There is also a second way to bring Emrakul into play: Windbrisk Heights. If you manage to put an Emrakul under this and attack with 3 creatures (which should not be hard), Emrakul comes in play for only 2 mana.
This is not a budget deck but it is also not prohibitively expensive. You will need a few shock lands and 8 fetch lands (KTK only if you prefer; 4x Windswept Heath and 4x Flooded Strand), as well as a few expensive cards such as Thoughtseize and Emrakul, the Aeons Torn. Maybe you can still get your hands on the Modern Masters BW Tokens Event deck from 2014 to get you started.