Heidern style assassination techniques is the name of a group of disciplines developped by Heidern and taught to the Ikari Warriors. Known practitioners of these disciplines are Heidern himself, Ralf Jones, Clark Still, Leona and Whip.
All members of the Ikari Warriors team have been noted to use Heidern style assassination techniques despite all of them having different fighting styles, with the exception of Heidern and Leona. It can be inferred that these techniques make a complex fighting method, with the philosophy of taking each practitioner's strongest asset and making a weapon out of it. Ralf evolved his power brawling, Clark evolved his wrestling and Whip evolved her whip fighting. With this in mind, the Heidern system of military combatives is not only an inclusive hybrid, but also a specific martial art in and on itself. Interpreting Heidern's fighting style as the purest interpretation of the system, it can be understood that the Ikari Warriors may choose to improve their own fighting style or to learn Heidern's killing techniques, which was the case with Leona.
In this case, the discipline encompasses stealth, espionage, use of firearms and explosives, and hand-to-hand combat. Taking into consideration the military context of the system, Heidern style assassination techniques focuses on fast and effective ways of killing. Heidern and Leona both wear a pair of black gloves, and when striking with open hands, they are capable of cutting the opponent. If this is supernatural or if the gloves are bladed somehow, is unknown. It is implied to be supernatural, since both Heidern and Leona are capable of creating projectiles and arcs of slashing energy. Another supernatural aspect is the ability to siphon vital energy from an opponent, something Heidern has extensively mastered, and Leona sparingly uses.
Other techniques employed by Heidern and Leona focus on the use of explosives. Leona uses her earrings, which are in fact small bombs, in combat. Leona and Heidern also conceal explosives in their gloves, and will mercilessly pierce the enemy in the gut and planting a small explosive inside in order to finish him off. The hand-to-hand aspect of Heidern's system focuses on biding time and punishing the opponent's mistakes, mirrored in both Heidern and Leona's charging special moves. When a miscalculation is made by the opponent, the practitioner of Heidern's assassination techniques punishes him with all his/her deadly arsenal of moves.
Stealth may also be an integral part of Heidern's system, as evidenced in his intro in KOF '98 and '01. In this intro, Heidern seems to blend with the shadows and suddenly appears. Taking into consideration that Heidern focuses on assassination techniques, stealth should be a primary concern of practitioners of the system.
This style of combatives may be taught to all the Ikari Warriors, but the following are characters verified to use the style.