"Borrel", known as "Varrel" (ヴァレル Vareru) in the Japanese version, is an archetype of DARK Dragon Link Monsters used by Varis. The archetype is related to the "Rokket" archetype, which is also used by Varis.
Both the English and Japanese names of the archetype are wordplays on gun barrels. The French and English names may reference the mathematical concept of Borel sets.
The archetype synergizes well with the "Rokket" archetype, seeing how "Borreload Dragon" is able to trigger the primary effects of all "Rokket" monsters to gain field advantage. The secondary effects of the "Rokket" monsters will also activate, summoning another monster in their place It is also able to snatch other monsters the opponent controls and cannot be targeted by said monsters' effects. "Borrelsword Dragon" on the other hand, while still able to activate the effects of "Rokket" monsters, is also able to increase its own ATK and halve the ATK of a monster your opponent controls. Coupled with the bonus to attack twice in the same should the first effect resolve, one could potentially get rid of most monsters in the game with higher ATK values such as "Number S39: Utopia the Lightning". "Borrelguard Dragon" is immune to effect destruction and can revive any monster destroyed during the turn the effect is used provided the player has a Spell or Trap Card in their Spell & Trap Card Zone to sacrifice, although the revived monsters' effects are negated. Like "Borrelsword", it also changes monsters' battle positions.
Monsters such as "Booster Dragon" can also help, acting as weaker version of "Borreload". "Miniborrel Dragon" is also useful due to being able to recycle itself once a turn as long as the player controls a "Borrel" monster, albeit at the cost of tributing a Link-3 monster they control.
The Spell and Trap Cards of the archetype are also useful; "Borrel Regenerator" can help recycle monsters more, and should the equipped monster summoned with it be destroyed the player draws 1 card. "Borrel Cooling" essentially allows "Borreload", "Borrelsword" and "Borrelguard" to activate even more "Rokket" effects.