Once per turn, if your opponent activates a monster effect (except during the Damage Step): You can make this card gain 1000 ATK
It's possible to add 4 Lavals at once via 3 Handmaidens, and if you send them with Flame Wheel Spin or Molten Conduction Field, you can gain 5 at once
Opinions may vary, but I find the cards listed below to be very splashable and are strong supportive cards to add into nearly all of my decks
Tristan is a great friend who would do anything to support the people he cares about
basic rules down pat: Fusion Monsters are made by combining other cards via an effect
That said, unless you are planning on opening a lot of boxes (to help even out variance), I'd probably plan on getting the non- Masterpiece value and treat the possibility of opening a super-sweet, super-expensive Invocation as a bonus lottery ticket that you get for free when buying a box of Amonkhet