If you have the spirit to spare Magesworn can often shut down Arcanyst variants as it prevents them from playing the cheap spells that fuel their synergies, including their BBS’ and pretty much all their single-target removal. Besides that, as mentioned Lightbenders are a cheap investment that work very well as counters to minion-based decks like Arcanar.
Honestly I have had success with Healonar recently, but mine makes heavy use of cards from several expansions, particularly Unearthed Prophecy which gave Hallowed Ground to Lyonar which hands out heal procs like a low-rent hooker hands out VD.
However it is definitely not S-tier and loses out to a lot of the top-tier decks at the moment.
If you have a decent collection or grounding in some of the other factions you may try building a budget deck for that faction, as Lyonar is kind of down on their luck right now besides Swarm variants.

. Plus it was initially made before kara’s bloodborn spell got nerfed, but it was still definitely playable after it… but now, ehhhhh…