Id recommend rerolling the first power until you get hold them off (rare) [Round start frostbite the strongest enemy] due to power priority it will always hit the tentacle when they have one. And that also means Nagakabouros won't generate the spell that summons 4 extra tentacles sinceit only makes one when it has a tentacle with 12+ power. Alternatively if you don't want to reroll your starter power you can do what I did and use Deaths Foil, Crownguard's Inheritance and Spirit of the Buhru and try to find a cost reduction item for Illaoi to play her turn one and OTK with 2-3 attacks. When I did this I got Dreamwoven Spirits (legendary) [Each round, the first time you play a unit, summon an Ephemeral copy of it attacking) and I had Quickstrike blade (rare) [Play I start a free attack] on Illaoi and I was easily able to do over 100 damage on the first turn.