The first 3 cards are Hex-sealed fusion cards. They can substitute for other fusion materials. The first two spells are Tribute to the doomed which can destroy a monster and Fusion Recycling Plant that can search Polymerization and return fusion materials from the grave.
you can replace hex sealed fusions with any fusion subsitute and tribute to the doomed is just in case he gets lv10 on board before you get paladin to stop his summon, you can replace recycling plant with fusion sage or if you don't have it crystal seer
What’s to stop him from tribute summoning his lvl 5, then using Give and Take to summon a weak monster to our side and attacking it, leading to lvl 7, then lvl 10?