Well hello, here iam again with a little improved build on elise
i play her alot and it's so easy to harras ppl with her.
i will tell u my build

Well, as you might have seen, i have chosen for ignite and flash.

Flash= easy for escapes or yust for entering teamfights
ingite= yust for dealing the finishing blow on a champion

other great choises would be:
ingite and ghost becouse with ghost you can escape even more easly

you might like other spells but NEVER EVER NEVER TAKE REVIVE PROMOTE Or the other noob spells
noone likes u if u take those! be aware

Okey now im explaining you a powerfull combo to bring down a champion easy without getting yourself getting hurt alot

as you enter a 1v1 fight try to be in human form and cast ur E to stun, if your stun hit try to land ur W and Q in human form as fast that u can on ur enemy. after that change to spider, use ur Q to get a little closer to the enemy and use ur W to melee hit him faster if he decides to use flash or something use ur E to catch up with him, well ur spells might be on cooldown so in that case switch back to human and harras him with ur combo again, if hes verry low hp just a little out of range for ur melee attacks and if ur spells on cooldown use ur ignite to deal the finishing blow

For Teamfights:
Well if you decide to go in a teamfight, try to land ur stun as fast as posible on the weakest target Example Ezreal, then cast ur stun kinda near Ezreal but also try to hit as many enemys as posible, then continous with ur combo, cast Q on lowest hp target(at this moment ezreal should be if not find other (becouse ur Q deals most damage on low hp target if ur human form)
Switch to spider form and use ur q to leap towards Ezreal (the weakest target) quickly press ur w also to gain health and harras him, NOTICE: EZREAL MIGHT FLASH AWAY WITH SKILL so if he does then yust use ur e in spider form and catch up to him, land ignite and he should be death, if not go back human use stun and do ur combo again (Human form E W Q then spider form
Q W (e) he should be death easly, go back to team and find ur next target.