What the format changes

Every “each opponent” clause resolves twice in 2HG, and both halves come off one shared life total. These are the cards that quietly double in power.

Forcing both opponents to sacrifice strips two boards for one card. This is the classic 2HG blowout.

“Each opponent discards” is a two-for-one in 2HG. Syphon Mind and its relatives jump several tiers here.

Teammates take one turn together, so an extra turn is an extra turn for both players. Few effects gain more from the format than these.

A wrath answers two opponents' boards at once in 2HG, and destroys your teammate's along with them. One-sided and modal sweepers gain the most.

“Target player” and “target permanent” effects can be aimed at your partner — something no duel format lets you do.

You defend against two attacking players out of one shared pool, so a single fog can buy your team a whole turn.

Drain and burn that reads “each opponent” lands twice on a single shared life pool, so the printed number is effectively doubled.

Stax effects tax two opponents for the price of one — provided your own teammate can play through them.

“Whenever an opponent…” watches two players instead of one, so these triggers pay out roughly twice as often as they do in a duel.

Turns are shared and fast in 2HG. Cheap answers let you hold up interaction without giving up your own development.

A 2HG team loses at 15 poison counters rather than 10, so infect and toxic need half again as much work to close a game.

Shared draw feeds two opponents and only one teammate. These cards read well and play badly in Two-Headed Giant.

Two opponents deploy two boards. Expensive spot removal trades down unless it is cheap or hits more than one permanent.

A bigger shared pool makes small lifegain proportionally weaker — and it is the same pool your teammate is already spending.

Effects that name “target opponent” only ever reach half the enemy team, so they lose reach in a format with two.

In 2HG the monarch is one player, not the team. The other team can send both players' creatures at that head in one combined attack, so the crown is hard to keep.

“Creatures you control” stops at your own board. Your teammate's creatures are untouched, so anthems are worse than they look.