"Armed Dragon LV3" and "Armed Dragon LV5" in the artwork of "Level Change"
"Armed Dragon" (アームド・ドラゴン Āmudo Doragon) is a series of monsters introduced in Soul of the Duelist, with further support in Duelist Pack 2: Chazz Princeton. All members of this series are Dragon-Type (except "Metaphys Armed Dragon" that is a Wyrm-Type), which means Dragon support cards are all effective with them. The majority of "Armed Dragon" monsters are also LV Monsters. In the Yu-Gi-Oh! GX anime, Chazz Princeton obtains these cards while at North Academy and uses them through many of his appearances. Most of the "Armed Dragons" are of the WIND Attribute.
The original "Armed Dragon" series focused on sending cards from the hand to the Graveyard to destroy monsters on the field. Depending on the ATK of the monster sent, certain monsters could be destroyed while others were not. This is why cards that decrease your opponent's monsters attack, such as "Shrink" and "Burden of the Mighty" can be helpful. "Armed Dragon LV10", being the strongest, simply destroys all face-up monsters regardless of their ATK and any card could be sent from the hand to the Graveyard, rather than only monsters, as was the case with the lesser forms. This series is one of two "LV" Dragon series (the other being the "Horus the Black Flame Dragon" archetype).