Cast Realm-Scorcher Hellkite by paying 4 and sacrificing another artifact, enchantment or token.
When Realm-Scorcher Hellkite enters the battlefield, it and Lathliss trigger twice.
Resolve both Realm-Scorcher Hellkite triggers, adding 5.
Resolve both Lathliss triggers, creating two 5/5 Dragon creature tokens.
Activate Temur Sabertooth by paying 1, returning Realm-Scorcher Hellkite to your hand from the battlefield.
Repeat.
This loop is a masterclass in draconic recycling, anchored by Realm-Scorcher Hellkite's bargained entry producing extra mana to help sustain the cycle. With Panharmonicon doubling every entry trigger, casting Realm-Scorcher Hellkite triggers its own mana-generation twice alongside Lathliss, Dragon Queen, immediately spawning a pair of 5/5 Dragon tokens to keep the sky thick with scaled menaces. You then use Temur Sabertooth's activation to bounce the Hellkite back to your hand for a modest investment of mana, leaving you with more than enough resources left over to recast it and repeat the whole explosive process.