Similarly to counterattack special moves, Corrin will briefly pose, and if an attack hits them during this time, they will evade the attack and strike back with surges of water in front of and behind them, reflecting back 1.2x the damage on both sides (with a minimum of 10% damage dealt to each opponent struck). Corrin utilizes his Dragon Fang for this attack, morphing into his dragon form to stomp the ground with both front feet as they retaliate (akin to their down throw). The move deals more knockback when the counterattack hits as early as possible, making its hitbox akin to a sex kick.
Unlike other counterattacks, Counter Surge bears several unique distinctions: it launches opponents on a vertical trajectory, defends Corrin equally from front and back rather than only in the direction they are facing, and Corrin outright evades the attack rather than absorbing it, meaning that nearby opponents can be hit by the dodged attacks while incoming projectiles will not dissipate.
Upon Corrin's debut and prior to the 1.1.5 patch, the move's damage multiplier was originally 1.3x. By virtue of its nearly purely vertical knockback, this made it easily the strongest non-custom counter in the game in terms of KO power (surpassing even Shulk's Vision and Roy's Counter), being capable of OHKOing after countering a hitbox dealing at least 33% damage, a lower requirement than any other counter move (apart from the custom special move Power Vision, which can OHKO with a hitbox dealing only 30% damage). In the 1.1.5 update, the damage multiplier was reduced to 1.2x and the counter window of the move was reduced, making it less powerful and more in line with the other aforementioned counters.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Like the other DLC characters, Corrin has no custom move variations.
Counter Surge is based on a core element of Fire Emblem gameplay: in all games of the series, when a unit attacks another unit, the targeted unit will perform a counter-attack to strike back at their attacker if they currently have an equipped weapon with a compatible range. In addition, some of the games have a Counter skill that reflects half or all damage (depending on the game, with varying rates of occurrence). Corrin in particular can learn the skill itself in their home game by reclassing into the Oni Chieftain class tree, and their use of their dragon form is reminiscent of the attack pattern while equipped with a dragonstone.
While the term 竜穿 translates more literally to "dragon drill", the games even in the Japanese versions dub it contextually as "Dragon Fang".