Q: If "Gem-Knight Seraphinite" is face-up in my Monster Zone, and I performed an additional Normal Summon this turn using its effect, can I then activate the effect of "Knightmare Goblin" when it is Link Summoned?
A: In this scenario, if you already performed an additional Normal Summon this turn using the effect of "Gem-Knight Seraphinite", you cannot activate the effect of "Knightmare Goblin". However, even if "Gem-Knight Seraphinite" is face-up on your field, but you did not perform an additional Normal Summon this turn yet, you can activate the effect of "Knightmare Goblin" when it is Link Summoned. Afterward, you can perform 1 additional Normal Summon using either the effect of "Gem-Knight Seraphinite" or the effect of "Knightmare Goblin". (You cannot gain an additional Normal Summon with both effects.)[2]