msem-instigator

Whenever another legendary creature you control enters, put a +1/+1 counter on The Lost and Seeking.
Surpass {4}{R}{W} ({4}{R}{W}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

As this permanent transforms into Velir, put four loyalty counters on it.
[+1]: Draw two cards, then discard two cards unless you discard a land card.
[–2]: Search your library for a multicolored card, reveal it, put it into your hand, then shuffle.
[–4]: Exile target permanent.

[+2]: Put a -1/-1 counter on or remove a -1/-1 counter from up to one target creature.
[–1]: Draw a card, then each player sacrifices a nonland permanent.
[–10]: Destroy all nonland permanents you don't control.