@examples of bhvAdi verb stems

More than half of the roots are /bhvAdi. This means that they get /zap in the /laT, /laG, /loT, hard liG.

The /zap causes gbH of the last vowel —

bhU भू + /laT
→ bhU भू + /zap + /laT by kartarizap
→ bho भो + /zap + /laT by gbH
→ !**bhava- भवॱ + /laT by ecoyavAyAvaH

So we get —

**bhava- भवॱ + /laT /tip → **bhavati भवति "is", "becomes"

**bhava- भवॱ + /laT /sip → !**bhavasi भवसि "thou arst", "becomest"

**bhava- भवॱ + /laT /mip
→ bhavA- भवाॱ + /mip by atodIrghoyaJi
→ !**bhavAmi भवामि "I am", "I become"

**bhava- भवॱ + /laT /jhi
→ bhava भव + anti अन्ति by jhontaH
→ bhavanti भवन्ति by atoguNe
→ !**bhavanti भवन्ति "they are", "they become"

ji जि + /laT → **jaya- जयॱ + /laT

or of the nexttolast light vowel, by pugantalagh... —

zuc शुच् + /laT → **zoca- शोचॱ + /laT

nexttolast heavy vowels do not get /guNa —

IkS ईक्ष् + /laT
→ !**IkSa- ईक्षॱ + /laT

jIv जीव् + /laT
→ !**jIva- जीवॱ + /laT

iS इष् + /laT
→ iS इष् + /zap + /laT
→ ich इछ् + /zap + /laT by iSugamiy...
→ icch इच्छ् + /zap + /laT by checa
→ **iccha- इच्छॱ + /laT

And nexttolast a अ of course stays unchanged —

paTh पठ् + /laT → !**paTha- पठॱ + /laT

In the /laG, the root gets, in addition to the above, also /aT or /AT from luGlaGlRGkSvaD... or ATazca —

bhU भू + /laG
→ abhU अभू + /laG by luGlaGlRGkSvaD...
→ !**abhava- अभवॱ + /laG by the same steps in **bhava- भवॱ

zuc शुच् + /laG
→ !**azoca- अशोचॱ + /laG

nI नी + /laG → **anaya- अनयॱ + /laG

iS इष् + /laG
→ (/AT + iS इष् + /zap) + /laG
→ !**aiccha- ऐच्छॱ + /laG with cch च्छ् like in **icchati इच्छति

You said hard liG. What about the soft liG?

Soft tenses are unaffected by kartarizap, so bhU भू gets no /zap and no gbH. Example: **bhUyAt भूयात्.