Yesterday, Prysmatic Labs announced the launch of their next eth2 test network release called Onyx. This new testnet will run a full mainnet configuration using the latest phase 0 spec (v0.12.1) and is fully multi-client ready. This spec version is also the target for eth2 phase 0 mainnet (barring any significant bugs/errors). The genesis event for this testnet is set to happen very soon. If you want to participate, you can check out this video guide