Not sure what a "gate wizard" is - A wizard using [mwcard=MW1J07]Gate to Voltari[/mwcard]? Does the wizard have any other spells?
Anyway, yes, I think there is definitely a "rock-paper-scissors" aspect to Mage Wars Arena. Assuming roughly equal player skill, I am of the opinion that:
- My curse-based Arraxian Crown Warlock is strong against most mages (and especially heavily armored mages) but has almost no way to win against a Necromancer;
- My [mwcard=FWC08]Invisible Stalker[/mwcard] Forcemaster is strong against many mages but has almost no way to win against a Wizard ('cause unlimited Ethereal quick-spell ranged attacks, which cut through both the Stalker and Mind's Eye like a warm knife through butter);
- My [mwcard=MWSTX1CKC01]Bridge Troll[/mwcard] Forcemaster is strong against many mages but struggles against Fire-based mages ('cause Troll has Flame +2 and no built-in armor);
- My [mwcard=MW1C26]Necropian Vampiress[/mwcard] Forcemaster is strong against many mages but struggles against Undead swarms ('cause Vampiress only gets Vampiric vs living, and undead are generally Psychic-Immune, etc).
- A well-played Druid is strong against many mages but has more trouble with Warlocks ('cause Flame +X, and mostly [mwcard=MW1J19]Deathlock[/mwcard]);
- Necromancers are strong against many mage types but have more trouble against Holy mages ('cause of all the "+X vs Undead" effects);
- Priest can have not-terrible match-ups, but pity the Priest who comes up against an Adramelech Warlock!
Yes, if there is a vast difference in player skill, the more skilled player will almost always win despite the match-up. But for players close in skill, the match-up can be a very uphill/downhill battle for some match-ups.
Another way to think about it: There are many "counters" in the game, and you generally can't afford all of them (which is a good thing, actually, because it makes for interesting deck-building). If a mage is willing to spend sbp's on counters to living creature swarms (e.g. perhaps has cheap access to Idol of Pestilence and/or Suppression Orb and/or Mordok's Obelisk and/or Pillar of Righteous Flame, etc), then they're going to have an easy time against a mage whose primary game plan is to spam living creatures. A curse-heavy mage easily counters a mage based around armor. Banish can ruin the day of a single-big-buffed-buddy build. Purge Magic can wreck a curse-based mage. Waterfall Cloak and Raincloud can counter a Burn-based mage who doesn't have any answers to them. Chitin Armor + Waterfall Cloak, with protection, can counter a Jelly pit (at least until they're Dissolved). Psychic-Immunity ruins a Song-based Siren.
If a mage has enough counters (or has counters built in to their mage abilities, like Ethereal attacks or an inherent way to move Burn tokens, etc), that mage becomes scissors to the opposing paper to some degree. Maybe not 100-0, or even 90-10, but it almost certainly isn't 50-50.