Arena guide

1. Arena may change pretty soon, we don't have much info on what's upcoming.
2. Warlord 4 is generally considered to be a very difficult feat to even succeed in, much less Speedrun.
3. As you mentioned, one of the goals for speedrunning Explore is to help cultivate strategies to improve farming.
People do farm Arena, for obtaining Trophies. This provides Trophies at a higher rate per battle and per time than PvP does, and is almost exclusively done on Normal.
Thus, I propose the Speedrun category mandate a difficulty of Normal.

satyamfg

Gems of War

Xbox 360

PlayStation 4

Spydercaughtafly

Crisp_Purpose

McDoubleDad

USA / NTSC

Scylla

King Silenus

Goblins

Infernal King

Magnus

Garuda

Mouse

Mouse + Pad

Rowanne

Tesla

Scorpius

Megavore

Mobile

Skull team

Zuul'Goth

Phoenicia

Team swap

All-Seeing Eye

City of Thieves

Crypt Keepers

Dark Pits

Hall of Guardians

Mirrored Halls

Stonesong Eyrie

Dawnbringer

Wild Queen

Lord of Slaughter

Diamantina

Eldrazhor

Wild Court

Enemy

Input device

Team

Delve

Weapon

Hero (e12)

Hero (pet)

Hero (delve)

Android

Switch

GOW Gnome

KartSeven

HugeOgre

Crazy_na_rasslabone