You can send another "Laval Volcano Handmaiden" from your Deck to your Graveyard with this card, then use the effect of the second "Handmaiden" to send a third "Handmaiden", then use that "Handmaiden" to send another "Laval" monster to the Graveyard, for a total of 4 "Laval" monsters.
If you Synchro Summon "Lavalval Dragon", you can then return 2 of your opponent's cards to the hand.
Activate the effect of "Laval Miller" or "Molten Conduction Field". Send 1 "Laval Lakeside Lady" and 1 "Laval Volcano Handmaiden" to the Graveyard. Then, activate the effect of that "Handmaiden" to send another "Handmaiden". Then use the second "Handmaiden" to send a third "Handmaiden". Use the last "Handmaiden" to send a different "Laval" monster to the Graveyard, then activate the effect of "Laval Lakeside Lady" to destroy a Set card.
You can dump multiple copies of this card to the Graveyard with "Painful Choice" and activate their effects at the same time. Assuming your opponent picks one of the three "Handmaidens" to go to your hand, and the other monsters you send are also "Laval" monsters, you can get 6 "Laval" monsters in the Graveyard at once.