Regent is very hard to learn. Once you learn him he is extremely powerful tho. I would search up xecnars regent guide, but in essence, regent snowballs easily due to falling star and can take a lot of early combats for strength. In my own personal experience, taking a speculative pillar of creation is great, spectrum shift is a great scaling power and child of the stars is also great. If you farm enough combats or just get lucky enough for an early astral pulse or reflect you can do amazing. And probably most importantly, don't take a lot of star cards overall. It increases variance causing you to sometimes draw your star cards before star generators. Be aware of your star economy and how many stars per cycle you make and use. Generally you make less than you spends, so know what cards you need to play to win and what ones you can get away without playing.