"As soon as the board game started, it was clear that (
name) was in his form, selfishly making moves that benefited only him and sabotaged the rest of us."
"When (
name) gets into her form, she becomes overly competitive, turning a friendly game of trivia into a battleground."
"(
Name) was in his form at the party, dominating the conversation and not letting anyone else get a word in."